Drury said...
Do you just want the kite to be fast? Where are you riding, what are the conditions like, how much do you weigh, what kind of tricks can you do at the moment, and what are you looking to progress to?
You're asking these questions as if one can actually give an answer to the original question....
The best kite, like the 'best' of any depreciating asset, is the one that's not going to cost you a bucket load of money for very little improvement in functionality, most commonly the one you already own.