Just got a rabbit air after a bunch of research. It does hepa filtration as well as odor. May get a second unit, likely the Conway 1512 to increasey coverage.

One thing to look at is cost analysis of the filters. Many brands may be great but I found it ridiculous how after 2 years you could be paying more than double what your air purifier costs.

My rabbit air a3 will cost around 120 bucks 1x a year as the machine is meant to run 24/7.

Another thing is warranty. Rabbit air offers 5 years which is great. For my son's bedroom we went with a levoit as they are relatively inexpensive to keep up and running.

Blue air is nice but some of the models I don't like their prefilter. It's basically some cloth that slips over the bottom. Which brings me to another point. Washable prefilters.

Overall, in your search you need to look for something with a washable prefilters, reasonably priced filters, ideally good on power consumption, and one with a good cadr.

If you suffer from Allergies you ideally want your purifier to do 4+ air changes per hour. Depending on how open the space is you may need 2 units or more. Which is precisely why I'm looking for a second to ensure that.

As for cadr. You need to do some math to figure out what you need. Room area x height of ceiling to get cubic feet.

Then take cadr and multiply it by 60 to get cubic feet per hour.

Take that and divide by the room size. The higher the better.