Thanks so much everyone, this is actually really helpful 
GonzMonz , that real-world example honestly sold me more than any review 
the fact that it reacts that quickly to smoke and aerosols is exactly what I need since my allergies get triggered super easily. good to know it’s quiet too because sleep has been one of my biggest issues lately.
Pshores, interesting point about the app. i didn’t think i’d care much about that at first, but being able to actually see the air quality improving sounds pretty useful, especially if i’m running it most of the day.
i’m definitely leaning more towards the LEVOIT Air Purifier (Core 400S) now just because multiple people here are using it daily and it seems reliable long-term.
that said, i’m still a bit curious about the BLUEAIR one since i’ve seen a lot of mentions about its filtration system being really strong for allergens.
Simonb, that Dyson model sounds amazing (and yeah… a bit overkill for my situation 
), but I’m trying to stay a bit more budget-friendly for now.
quick question for anyone who’s tried both or similar,
do you notice a big difference in dust reduction and night-time breathing/sleep quality between brands, or are they all pretty similar once you get into this range?