I have a couple BlueAir purifiers. They both work well, especially when I use the charcoal filter for smoke. I recommend the 400 series or above. Filter needs to be replaced every 6 months, maybe more if you use lots of moxa stick or compressed/smoky moxa. The filters alone run about $100 each, so be aware of that. Zero complaints from others in my office building after almost 6 years of heavy use.
Last year, I switched to direct moxa. This requires no ventilation or air purifier at all... even in rooms with no windows.