My wife and I have a townhome that has a lot of allergens left in the carpet. We have shampooed the carpets and it is still bad. It seems like our vacuum does nothing to the carpet right now and is a little worn down. I am planning on buying a Dyson for her and have read good things about the animal and the DC-24 ball. What is the absolute best model? If not a dyson what is the absolute best vacuum? I like Kirby but they are pretty heavy and expensive.