
Coway
Airmega AP-1512HH Mighty
Durable, effective for allergens/odors, but loud on high.
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I have four BlueAir units. I bought the first one in 2020, and they haven't stopped working a single day since. I live in Jakarta, and I have plenty of proof to verify their quality. Mine are ProL, ProM, Classic 402, and BluePure. I like to keep them oversized so I can keep them running at the lowest possible speed. I don't have much experience with other brands, but I think BlueAir units with quality certifications are a good buy. I have allergies and asthma.
I also have a couple of BlueAir and the scheduling feature for smart purifiers is very nice to have. I have it set to run on the lowest fan setting all the time which is so quiet it's undetectable, and ramp it up for a few hours in the afternoon right before we get home from work.
Multi level approach works well. - Decent filter you change more regularly for your HVAC (agree with others that MERV shouldn't be too high) - Clean floors, if you have carpet get a deep carpet cleaning annually - Room air filters. I've had luck with Blue Air. Have one jig one for living room and some small ones for the bedrooms. - Have you tried using regular saline rinses for your nose? I use the powder saline mixes with the plastic applicator from NeilMed, but there are others out there. While my allergies are pretty mild, I haven't needed to take any allergy medicine at all since using these.
The replacement filters cost too much and hold only 4ish months
I bought the shark never change as my first purifier just recently and I feel the difference with my allergies. The 5 year filter change really attracted me but after reading here a little more I might need to change it more frequently. I also tried the blue air for my office but didn't like it, I didn't feel any difference and it was noisy, I returned it and got the smaller shark never change .
I also really like Blue Air and mine are all 6+ years old at this point.

Coway
Airmega AP-1512HH Mighty
Durable, effective for allergens/odors, but loud on high.

Levoit
Vital 200S-P
Smart, effective dust/odor; some find replacement filters pricey.

Winix
5500-2
Budget king, durable; poor VOC removal, Plasmawave disliked.

Coway
Airmega Mighty
Durable, great for allergies/dust, responsive auto-fan.

Winix
5510 & 5520
Good value, durable, effective for pets; carbon filter issues.

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IKEA - UPPÅTVIND

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CleanAirKits - Corsi-Rosenthal Box

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Austin Air - Healthmate Plus

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Winix - 5500-2

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Coway - Airmega 400

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Coway - Airmega AP-1512HH Mighty