I bought the Alen Breath Smart Fit 50 and I love it. I have an open house setting so it has a lot of work to do and it does it's job perfectly. I have a household that includes a long hair constantly shedding dog and two cats. I have my air purifier in my kitchen/great room area. I purchased it primarily for two reason. The first is to help with the pet hair and the second is the dust. I also wanted something attractive and quiet. I got all that plus odor control and allergen control among other features.
I set it on auto and let it do it's job. It goes into the proper speed depending on what's going on at that time. For instance if I'm cooking or cleaning it adjusts itself to turbo mode. I could probably go on and on but the bottom line is it is the perfect unit for what it says it does.