Bigger hepa units on low work much more quietly than a small unit on high. Fyi. The boxes usually over estimate the room area they can clean. I always buy bigger units. There are a lot of reviews on Twitter. I have had some basic Honeywell units for many years.

Only buy a true HEPA despite the filter replacements. A filter with fancy ionization, etc that doesn't actually filter and clean the air is not doing its job. It's physics that you need the air to move to filter. MERV 13 to 16 AC filters attached to a box fan have most efficacy for moving and filtering the most air.