Rabbit Air BioGS still best
It's been over 3 years since we first bought the RabbitAir BioGS 421A Air Purifier, and the performance has remained exceptional.
One thing we've noticed is that you can get a lot of life out of your filters if you make a habit out of vacuuming / washing the charcoal filter and HEPA prefilter. This goes without saying, but it can be the difference between a filter lasting 9 months or 18 months. Fortunately replacement filters are cheap for the Rabbit BioGS compared to the others.
The RabbitAir BioGS 421A Purifier has been most effective on the auto-setting in rooms slightly smaller than the given coverage (600 square feet). Auto setting will start the Rabbit on high for a few minutes and then slow down to a consistent level as it manages the odor sensors. In this way, it will then do a great job of saving power / energy and taking care of odors and dust when the sensor detects changes. Even when working at full speed the machine sounds like a fan on low speed.