Which is the best air purifier?

I have recently bought an air purifier from www.healthwayuk.com. I saw a demostration measuring the cleanliness of the air. They showed that the air that was coming out of the machine was 100% pure!! We have one of these on our landing, and all of the rooms smell and feel cleaner because of it! I seem to be able to sleep easier at night with less congenstion in the morning! I would really recommend this product!