Coway

The Coway Airmega 200M is purification matched to the room that matters most. Sized for bedrooms up to 361 square feet, with a real-time air-quality indicator, filter-change alerts, and a sleep mode that runs at 24 decibels — quieter than the room itself.

The right-sizing argument beats the big-unit argument for most homes: you spend a third of your life in one room, so treat that room properly. At this price, one per bedroom is a rational plan rather than a splurge. The least dramatic product in the air category, and one of the most used.