I know I've slammed Consumer Reports before, but check what they have to say on this. On this at least, their testing shows which one will work well when brand-new. Durability is a roll of the dice with a vacuum, though. Also, look how easy it is to maintain the thing, such as bag access, filter access, and cleaning out the beater bar and the inevitable clog.
I really like our Dyson DC25 since the basic maintenance stuff on that is child's play to access. Cleaning hair from the beater brush takes a quarter to release the brush, and can be removed, cleaned, and replaced in less than 5 minutes. The filters are re-usable and easy-peasy to access. The attachments plain work. And, it works well as a vacuum. I like how maneuverable it is around furniture. It doesn't go under things well, but we have an attachment for that. I got it new for $350 IIRC, which is expensive. On the other hand, it's a very well-thought-out vacuum that works well for its intended purpose.