The Renpho AP-089 Air purifier is a very solid candidate which cracks our top three list. It has medical grade H13 filters (which rank higher than True HEPA) and can remove 99.97% of fine particles out of the air. This includes odor, dust, pet dander, and smoke. This air purifier can fully clean a room of 480 square feet within 30 minutes or less. Meaning, it will be even faster in a smaller room. At its price point, this air purifier stacks up very well compared to others that claim that much purifying capacity.
One knock on other purifiers is that some have bright lights that make it hard to sleep if they are positioned in the bedroom. This one is designed with that in mind, with a setting to turn off all display lights. It also features four speed settings, and an automatic mode which will cycle the speeds based on how many air particles it detects. Set it and forget it!
This comes comes with a lifetime support promise from Renpho, per their website. Available in white and black models.