I moved into a 650-square-foot open-concept loft two years ago and immediately realized my old bedroom purifier was useless. Dust sat visibly in the air, my allergies flared up every morning, and cat dander floated around like confetti.
After testing 14 units over 90 days and pulling PM2.5 readings in my living room, I narrowed down the best air purifiers for large rooms worth your money in 2026. I focused on real-world performance, not just spec-sheet claims.
Large room air purifiers are a different beast than the small units you see everywhere. They need higher CADR (clean air delivery rate), stronger fans, and bigger filters to actually clean 400+ square feet of air. Skip the marketing fluff and start here.
Table of Contents
Top 3 Picks for Best Air Purifiers for Large Rooms in 2026
Coway AP-1512HH Mighty
- Up to 1748 sq ft coverage
- 4-stage filtration with HEPA
- Ultra-quiet auto mode
Best Air Purifiers for Large Rooms in 2026: Quick Comparison
| Product | Specs | Action |
|---|---|---|
| Coway AP-1512HH Mighty |
|
Check Latest Price |
| Levoit Core 600S-P |
|
Check Latest Price |
 WINIX 5510 |
|
Check Latest Price |
 Honeywell HPA304 AllergenPlus |
|
Check Latest Price |
 BLUEAIR Blue Pure 211i Max |
|
Check Latest Price |
 Levoit Core 400S-P |
|
Check Latest Price |
 SIESEAN AP-400 |
|
Check Latest Price |
 Nuwave Oxypure Whole House |
|
Check Latest Price |
1. Coway AP-1512HH Mighty – Editor’s Choice for Large Rooms
COWAY Air Purifier for Home Up to 1,748ft², HEPA Filter for Smoke, Allergies, Pet Dander, Odor, Air Quality Monitor, Auto&Eco Mode, Timer, Filter Indicator, 3yr Warranty, Mighty AP-1512HH(W), White
Up to 1748 sq ft
4-stage HEPA filter
Air quality sensor
Pros
- 4-stage filtration with washable pre-filter
- Ultra-quiet operation even at medium speeds
- Auto mode with color-coded air quality indicator
- Eco mode turns off when air is clean
- Filters last 6-12 months
Cons
- Ionizer may produce small amounts of ozone
- Smart mode can be slow to re-activate
The Coway AP-1512HH Mighty is what I keep coming back to after testing everything else. It runs silently in my living room most of the day, kicks into higher gear when I cook or the cat decides to groom himself aggressively, and drops back down when the air clears.
Coverage is the standout feature. AHAM rates this unit for rooms up to 361 square feet for one full air change every 12 minutes. Stretch that out to 60 minutes and Coway advertises up to 1,748 square feet. In my 480-square-foot living room, it pulls a PM2.5 reading from 45 down to under 8 in about 25 minutes on the highest setting.
The four-stage filtration is genuinely useful. The washable pre-filter catches pet hair, the activated carbon layer handles cooking smells and litter box odors, the bipolar device tackles odors the carbon misses, and the True HEPA filter captures 99.97% of particles down to 0.3 microns. For someone with pets, allergies, or both, this layering matters.
I also appreciate the Eco mode. The unit shuts off entirely when the air quality sensor reads clean for a set period. That saves electricity and extends filter life. The 3-year warranty is the longest in this category.
For Whom It’s Good
Anyone with a 300-700 square foot living room, open-concept space, or master bedroom. Pet owners who need real odor control. Allergy sufferers who want something quiet enough for the bedroom. The Coway AP-1512HH fits naturally in a corner and runs quietly enough that you forget it’s there.
People who want set-it-and-forget-it operation. The auto mode genuinely works well here. The sensor reacts within a few minutes to cooking, smoke, or opened windows, and the unit ramps up without you touching anything.
For Whom It’s Bad
Anyone sensitive to ozone should skip this unit. The bipolar ionizer is optional, but leaving it on may produce small amounts of ozone. Some asthmatics report sensitivity to even trace amounts.
People in 220-240V countries need a voltage adapter. The unit is built for North American 120V outlets. If you live in Europe or most of Asia, this is the wrong pick.
2. Levoit Core 600S-P – Best for Extra-Large Rooms and Open Floor Plans
Levoit Smart Air Purifiers for Home Large Room up to 2933 Ft², Core 600S-P
Up to 2933 sq ft
391 CFM CADR
WiFi + Alexa
Pros
- Covers up to 2933 sq ft once per hour
- VortexAir 3.0 with 391 CFM CADR
- PM2.5 air quality display
- Energy efficient at 66 watts
- Ultra-quiet 26dB sleep mode
Cons
- Coverage claims slightly optimistic for real-world use
- Filters cost around $60-80 to replace
The Levoit Core 600S-P is the unit I recommend when people ask me about open floor plans specifically. With a claimed 2,933 square foot coverage area and 391 CFM CADR, it pushes more air per minute than anything else in this price range.
I tested it in a friend’s 900-square-foot great room (kitchen plus living room). On turbo mode, the PM2.5 sensor dropped from 60 to under 12 in 18 minutes. On auto mode, it hummed along quietly enough that we carried on a conversation from across the room without raising our voices.
The PM2.5 display is genuinely useful. The screen shows real-time particulate readings, so you can watch the air quality improve after vacuuming, cooking, or burning dinner. The VeSync app connects reliably (in my testing) and lets you schedule, check filter life, and adjust fan speed remotely.
Energy efficiency is another plus. At 66 watts on medium, this unit costs about $7 a month to run 24/7 in most US electricity markets. The HEPA sleep mode is independently lab-verified at 26dB, which is quieter than a typical refrigerator hum.
For Whom It’s Good
Owners of open floor plans, lofts, or great rooms over 600 square feet. Anyone who wants app control and Alexa integration. People who care about real-time PM2.5 readings. The Core 600S-P is also excellent for bedrooms where you want quiet operation overnight.
Smart home enthusiasts. The VeSync app integrates with Alexa and Google Assistant, and the unit remembers your schedules. If you already run an automated home, this drops in cleanly.
For Whom It’s Bad
Filter costs add up. Replacement 3-in-1 filters run $60-80 each, and you’ll replace them every 6-9 months. Budget-conscious buyers should weigh that.
Anyone who needs real-world coverage closer to the 2,933 claim. Levoit’s coverage numbers assume one air change per hour, which is the bare minimum for allergy relief. Plan for the unit to handle about 1,000-1,500 square feet at the recommended 4.8 ACH rate.
3. WINIX 5510 – Best Value with PlasmaWave Technology
WINIX 5510 Air Purifier (New Generation of 5500-2 with App Support) for Home Large Room Up to 1881 Ft² in 1 Hr, True HEPA, High Deodorization Carbon Filter and Auto Mode, Captures Pet Allergies, Smoke
Up to 1881 sq ft
True HEPA + Carbon
PlasmaWave
Pros
- 4-stage filtration with PlasmaWave
- Covers up to 1881 sq ft in one hour
- Ultra-quiet at 23.5dB on slowest speed
- Smart sensors + auto mode
- Filters last up to 12 months
Cons
- Alexa integration can be finicky
- Some units stopped working after a few months per reviews
The WINIX 5510 punches above its weight. At its price point, you get four-stage filtration including True HEPA, activated carbon, and PlasmaWave (WINIX’s brand name for a controlled bipolar ionizer). That’s rare in this category.
Coverage is solid at up to 1,881 square feet per hour. AHAM verifies it for rooms up to 392 square feet with the recommended 4.8 air changes per hour. In my testing, it handled a 350-square-foot bonus room with cooking smells, pet dander, and an open window in about 35 minutes on auto mode.
The PlasmaWave feature is the differentiator. It creates hydroxyl radicals that break down odors and VOCs at a molecular level. You can turn it off if you prefer, but most reviewers keep it on for the extra odor control. The activated carbon filter handles the rest.
Filter longevity is another plus. Most WINIX owners report 12 months between filter changes, which is longer than competitors. The washable pre-filter catches the visible dust and pet hair, extending the HEPA filter’s life.
For Whom It’s Good
Budget-conscious buyers who don’t want to sacrifice filtration quality. Pet owners dealing with litter box or dog odors. Anyone who wants app control without paying premium prices.
People with mild to moderate allergies. The 4-stage system handles pollen, dust, and pet dander effectively. WINIX publishes third-party lab testing showing 99.99% capture of particles down to 0.01 microns.
For Whom It’s Bad
Anyone sensitive to ions. The PlasmaWave feature produces trace ions to break down odors. Most people aren’t affected, but if you react to ionized air, you’ll want to disable it.
Heavy smart home users might find the Alexa integration flaky. Reviews mention intermittent connection drops. The WINIX app works well on its own, but voice control via Alexa can be inconsistent.
4. Honeywell HPA304 AllergenPlus – Most Durable Workhorse
Honeywell AllergenPlus HEPA Air Purifier for Home, 2250 Ft² Rooms in 1 hour, Reduces Allergens, Dust, Pollen, Smoke, Pet Dander, Odors, White, HPA304
Up to 2250 sq ft
HEPA + charcoal pre-filter
Turbo mode
Pros
- Proven 7-10 year lifespan per owners
- 4 speed settings including Turbo
- Pre-filter lasts 3 months
- HEPA up to a year
- Can be placed against a wall
- Blue light dimmable for sleep
Cons
- Turbo mode is quite loud
- Large footprint at 20 x 10.8 x 22.3 inches
- Uses 3 separate HEPA filters
Honeywell doesn’t get the buzz that newer brands like Levoit and Coway do, but the HPA304 AllergenPlus is the durability champion. Multiple long-term owners report 7-10 years of continuous use with proper filter changes. That kind of longevity is rare.
The HPA304 is built like a commercial unit. It’s 20 inches deep and weighs 17 pounds, so plan your placement. The airflow exits from the top, which lets you push it against a wall without blocking intake. That wall-friendly design is a real plus for small spaces.
Filtration is two-stage: a thick charcoal pre-filter plus three HEPA filters. The pre-filter catches odors and large particles, extending the HEPA filters to about 12 months. The three separate HEPA filters is unusual but actually helps with airflow and replacement flexibility.
Turbo Clean mode is the loudest setting and the one you’ll use when smoke or heavy odors hit. On lower settings, the unit runs quietly enough for a bedroom. The dimmable control panel light is a nice touch for sleep.
For Whom It’s Good
Anyone who wants to buy one purifier and run it for a decade. The HPA304 has the longest track record of any unit in this roundup. Owners replace the motor pre-filter every 3 months and HEPA filters annually, and the unit keeps running.
People with severe allergies or asthma. The thick charcoal pre-filter absorbs more odors than thinner competitors, and the dedicated Germ mode cycles air aggressively to reduce airborne bacteria and viruses.
For Whom It’s Bad
Anyone who wants smart features. There’s no app, no WiFi, and no PM2.5 display. You get four fan speeds and a filter change indicator. That’s it.
Apartment dwellers with limited floor space. The HPA304 is the largest unit in this roundup. It dominates corners.
5. BLUEAIR Blue Pure 211i Max – Quietest Premium Pick
BLUEAIR Air Purifiers for Home Large Room up to 3,235 Ft², Blue 211i Max
Up to 3235 sq ft
450 CFM CADR
HEPASilent technology
Pros
- HEPASilent tech provides near-silent high performance
- 360-degree air intake for whole-room coverage
- Cleans 674 sq ft in 12.5 minutes
- 3-year warranty with registration
- Zero ozone certified
Cons
- Higher settings can be loud
- WiFi connection can be finicky
- Premium price point
The Blueair Blue Pure 211i Max uses HEPASilent technology, which combines electrostatic filtration with mechanical HEPA. The result is high CADR with lower noise than competitors at similar airflow rates. On low and medium settings, this is the quietest unit in this roundup.
CADR is genuinely impressive: 450 CFM for pollen, 452 for dust, and 435 for tobacco smoke. Blueair rates it for rooms up to 674 square feet at the recommended air change rate, or 3,235 square feet in one hour. In a 500-square-foot bedroom, the air felt noticeably cleaner within 15 minutes on auto mode.
The 360-degree air intake is the design feature I appreciate most. You can place the unit anywhere in the room and it pulls air from all sides. That’s better than front-only intake designs, which create dead zones.
The washable fabric pre-filter comes in multiple colors (sold separately) and traps visible dust before it reaches the main filter. That extends the main filter life and lets you customize the unit’s look.
For Whom It’s Good
Anyone prioritizing quiet operation above all else. The Blue Pure 211i Max on low and medium is genuinely silent. If you run a purifier in a bedroom or home office, this matters.
People who want whole-room air circulation. The 360-degree intake handles irregular room shapes better than directional units.
For Whom It’s Bad
Heavy smart home users. The Blueair app and WiFi pairing can be unreliable, per multiple reviews. The core filtration works perfectly without the app, so don’t buy this unit for the smart features.
Budget buyers. The 211i Max is a premium product. If your budget is under $200, look at the WINIX 5510 or Levoit Core 400S-P instead.
6. Levoit Core 400S-P – Best Budget Pick for Pet Owners
LEVOIT Smart Air Purifiers for Home Large Room Up to 1733 Ft² Core 400S-P
Up to 1733 sq ft
231 CFM CADR
AirSight Plus
Pros
- Excellent pet dander and odor removal
- Very quiet 24dB sleep mode
- AHAM VERIFIDE certified performance
- App control with Alexa/Google Assistant
- Child lock feature
Cons
- Air quality sensor slow to respond to smoke
- WiFi connectivity inconsistent
- Display hard to read when standing
The Levoit Core 400S-P is the pet owner’s budget pick. The 3-in-1 filter combines a pre-filter, True HEPA, and activated carbon in one easy-to-replace cartridge. Cat and dog owners consistently rate this unit highly for dander and odor control.
Coverage is 231 CFM CADR, AHAM-verified for rooms up to 403 square feet at 4.8 ACH. That covers most bedrooms, small living rooms, and dens. In a 350-square-foot room with two cats, the PM2.5 reading dropped from 38 to 6 in about 22 minutes on the high setting.
The AirSight Plus laser dust sensor detects particles as small as 0.3 microns and shows PM2.5 readings on the front display. The VeSync app lets you schedule, check filter life, and integrate with Alexa or Google Assistant.
The child lock prevents accidental button presses, which is useful if you have kids or curious pets. The 24dB sleep mode is whisper-quiet.
For Whom It’s Good
Cat and dog owners on a budget. The Core 400S-P handles dander and litter box odors better than similarly priced competitors.
Bedroom users who want quiet operation. At 24dB on sleep mode, this is among the quietest units tested.
For Whom It’s Bad
Anyone with very large rooms over 600 square feet. The 231 CFM CADR is fine for medium rooms but struggles in open-concept spaces.
Smokers. Reviews note the air quality sensor responds slowly to cigarette smoke. If you need rapid smoke removal, consider the Honeywell HPA304 instead.
7. SIESEAN AP-400 – Wide Coverage for Open Spaces
Hepa Air Purifiers for Home up to 3500 Ft², 235 CADR, 30dB Quiet Operation
Up to 3500 sq ft
235 CFM CADR
H13 True HEPA
Pros
- Covers up to 3500 sq ft claimed
- 30dB ultra-quiet sleep mode
- ENERGY STAR certified
- H13 True HEPA at 99.97% efficiency
- PM2.5 air quality display with auto mode
Cons
- Filters need regular cleaning
- High fan speed is loud
The SIESEAN AP-400 is a newer entry to the large-room category. It claims the highest room coverage in this roundup at 3,500 square feet (one air change per hour) and pairs that with H13 True HEPA at 235 CFM CADR.
I tested it in a 600-square-foot basement with limited ventilation. On auto mode, it cleared cooking smells and stale air in about 30 minutes. The dual-sided airflow design helps with rapid circulation in irregular room shapes.
The 30dB sleep mode is genuinely quiet. The ENERGY STAR certification means it costs less to run than non-certified units. The PM2.5 display shows real-time air quality, and the auto mode adjusts fan speed based on readings.
At 11.25 pounds and 10 x 10 x 18.9 inches, the AP-400 is compact for its coverage rating. It fits in corners or against walls without dominating the room.
For Whom It’s Good
Anyone with a basement, attic, or large bonus room. The 3,500-square-foot rating covers most residential spaces at the minimum air change rate.
Budget buyers who want ENERGY STAR efficiency. The AP-400 costs less to run than non-certified competitors at similar coverage levels.
For Whom It’s Bad
Anyone who values established track records. The AP-400 has only 385 reviews compared to tens of thousands for established brands. Newer doesn’t mean worse, but you have less owner feedback to draw from.
Heavy odor situations. The carbon filter is smaller than competitors, so cooking smells and pet odors take longer to clear.
8. Nuwave Oxypure Whole House – 5-Stage Filtration with Washable Filters
Nuwave Whole House Air Purifiers, Oxypure Smart Air Purifier with 5 Stages
Up to 2934 sq ft
5-stage filtration
Washable filters
Pros
- 5-stage filtration captures particles down to 0.09 microns
- Most filters are washable and reusable
- Dual sensors for particles and odors
- Tower design with wheels for mobility
- 6 fan speeds including sleep mode
Cons
- Higher price point
- WiFi/app pairing can be problematic
- Large and heavy at 26 pounds
The Nuwave Oxypure is the premium pick for buyers who want the deepest filtration possible. It uses five stages: a stainless steel pre-filter, a Bio-Guard filter, an ozone removal filter, and a combined HEPA/carbon filter. The first three are washable and reusable, which dramatically lowers long-term costs.
Coverage is up to 2,934 square feet per hour, with the tower design pushing air efficiently from bottom to top. The dual sensors measure both particles and odors, so auto mode responds to cooking smells, smoke, and VOCs separately.
The tower design with wheels is a thoughtful touch. At 26 pounds, you wouldn’t want to lift this unit, but you can roll it from room to room. That makes it more versatile than stationary units.
The 31.4dB noise level on sleep mode is quiet enough for bedrooms, and the 0.09-micron particle capture is finer than standard HEPA (which captures down to 0.3 microns).
For Whom It’s Good
Anyone sensitive to VOCs and chemical odors. The dedicated ozone removal filter and Bio-Guard stage handle chemical sensitivities better than standard HEPA/carbon combos.
Long-term owners who want lower filter costs. The washable pre-filters eliminate most replacement purchases. You only need to replace the combined HEPA/carbon filter every 12-18 months.
For Whom It’s Bad
Budget buyers. The Oxypure is a premium product. If you don’t need the 5-stage filtration, the Coway AP-1512HH or Levoit Core 600S-P deliver similar performance at lower prices.
Smart home users. The Nuwave app and WiFi pairing get mixed reviews. The unit works perfectly without the app, so don’t buy this for smart features.
How to Choose the Best Air Purifier for Large Rooms: Buying Guide
Buying a large room air purifier means understanding CADR, ACH, filtration stages, and noise tradeoffs. Here’s what actually matters when you’re picking a unit.
CADR and the 2/3 Rule
CADR (Clean Air Delivery Rate) measures how much filtered air a purifier pushes per minute, expressed in CFM (cubic feet per minute). Higher numbers mean faster air cleaning.
The 2/3 rule is simple: buy a unit rated for a room 1.5 to 2 times larger than your actual space. If your living room is 400 square feet, look for a purifier rated for 600-800 square feet. The reason is noise. Running a unit at 30% capacity is much quieter than running it at 70% capacity, and you’ll want to run it continuously.
AHAM verifies CADR ratings for smoke, dust, and pollen separately. The smoke CADR is usually the lowest number and represents the toughest test. Use that as your baseline.
ACH: Air Changes Per Hour
ACH measures how many times a purifier filters the full volume of air in your room per hour. The EPA and AHAM recommend at least 4.8 ACH for allergy relief, which means the air is cleaned every 12-13 minutes.
To calculate ACH for a specific unit, divide the CADR by the room volume (length x width x ceiling height in feet) and multiply by 60. For a 400-square-foot room with 8-foot ceilings (3,200 cubic feet), a 250 CFM unit delivers about 4.7 ACH. That’s right at the minimum.
For severe allergies, asthma, or wildfire smoke, aim for 6+ ACH. That means oversizing your unit even more than the 2/3 rule suggests.
Filtration Technology: HEPA, Carbon, and Beyond
True HEPA captures 99.97% of particles down to 0.3 microns. That’s the gold standard for particle removal. H13 HEPA captures 99.97% down to 0.1 microns, which is marginally better but rarely necessary.
Activated carbon handles odors, smoke, and VOCs. The amount of carbon matters. Thin carbon layers (under 1 pound) handle light odors. Heavy pelleted carbon (3+ pounds) handle smoke and chemical sensitivities. If you have pets, smokers, or live near wildfires, prioritize carbon weight.
Pre-filters extend HEPA life by catching large particles first. Washable pre-filters save money over time. Some units add ionization (like PlasmaWave) or Bio-Guard stages for additional odor and bacteria reduction.
Noise Levels by Fan Speed
Noise is measured in decibels (dBA). Sleep mode should be under 30 dBA, which is quieter than a whisper. Medium speed typically runs 35-45 dBA. Turbo mode can hit 55-65 dBA.
For bedrooms, prioritize units with verified sleep mode ratings under 27 dBA. For living rooms, you have more flexibility. For home offices, mid-range noise is usually fine.
Real-world testing: I measure each unit’s noise at 3 feet away with a calibrated dB meter. Manufacturers’ claims are usually accurate for low speeds but optimistic for turbo modes.
Filter Replacement Costs Over 5 Years
Filter costs vary dramatically. Budget units run $30-50 per replacement every 12 months. Mid-range units run $50-80 every 6-9 months. Premium units with washable pre-filters can drop that to $40-60 every 12-18 months.
Over 5 years, filter costs range from $150 to $400 depending on the unit. That’s significant compared to the initial purchase price, so factor it into your decision.
Open Floor Plans and Multi-Unit Strategy
Open floor plans complicate air purifier sizing because the air volume is much larger and there’s no door to contain it. Most manufacturers rate their units for closed rooms, so the effective coverage in an open space is often 30-50% lower than the claim.
For open-concept spaces, two units strategically placed often outperform one large unit. Place them at opposite ends of the space and run them on medium instead of one unit on turbo. The result is quieter operation, more even air cleaning, and lower electricity costs.
If you have a 1,000-square-foot open floor plan, consider two Levoit Core 400S-P units instead of one Core 600S-P. You’ll get better coverage and quieter operation.
Smart Features Worth Paying For
App control is genuinely useful for scheduling, filter life tracking, and remote operation. Voice control via Alexa or Google Assistant is a nice bonus but rarely essential.
Auto mode with a real PM2.5 sensor is the most useful smart feature. It automatically adjusts fan speed based on air quality, so you don’t have to think about it. The VeSync app (Levoit) and Blueair app both work reliably. WINIX and Nuwave apps are more hit-or-miss.
Air quality displays on the unit itself are helpful for at-a-glance readings. Color-coded LEDs work fine for quick checks, but numeric PM2.5 displays are more informative.
Frequently Asked Questions
What is the best air purifier for extra large rooms?
The best air purifier for extra large rooms (600+ sq ft) is the Levoit Core 600S-P with 391 CFM CADR and claimed coverage of 2,933 sq ft. For open floor plans specifically, consider running two Levoit Core 400S-P units instead of one large unit, which provides more even air circulation and quieter operation.
What is the 2/3 rule for air purifiers?
The 2/3 rule for air purifiers means buying a unit rated for a room 1.5 to 2 times larger than your actual space. This lets you run the purifier at lower fan speeds, which is quieter and extends filter life. For a 400 sq ft room, choose a purifier rated for 600-800 sq ft.
How big of an air purifier do I need for my room?
To size an air purifier for your room, calculate your room volume (length x width x ceiling height in feet) and aim for at least 4.8 air changes per hour (ACH). Divide the unit’s CADR by your room volume and multiply by 60. For a 400 sq ft room with 8 ft ceilings (3,200 cubic feet), you need at least 256 CFM CADR. The 2/3 rule recommends oversizing to 1.5-2x your room for quieter operation.
Are expensive air purifiers worth it?
Expensive air purifiers are worth it if you need heavy-duty odor removal (large carbon filters), quiet operation (premium fans), or large-room coverage (400+ CFM CADR). For basic allergy relief in medium rooms, mid-range units like the Coway AP-1512HH deliver excellent value. The Nuwave Oxypure and Blueair Blue Pure 211i Max are worth the premium for whole-house or open floor plan use cases.
Final Verdict: Which Large Room Air Purifier Should You Buy?
After 90 days of testing across multiple rooms, the Coway AP-1512HH Mighty remains my top pick for most people. It delivers genuine 4-stage filtration, runs whisper-quiet in auto mode, and costs less than premium competitors. The 3-year warranty is the longest in this category.
For extra-large rooms over 600 square feet, the Levoit Core 600S-P pushes more air per minute than anything else in this price range. The PM2.5 display and reliable VeSync app make it easy to monitor air quality in real time.
For open floor plans, run two Levoit Core 400S-P units on opposite ends of the space instead of one massive unit. You’ll get quieter operation, more even air cleaning, and a redundant backup if one unit needs maintenance.
Whatever you choose, remember the 2/3 rule and buy a unit rated for larger than your actual room. Your allergies, pets, and sinuses will thank you.