kawasaki zx-6r, but i may be a bit partial as i own one

the kawa, honda, and gsxr are all pretty even in all the comparos i've read. they say get the 636 if you like that raw edge, and get the honda or gixxer if you like smooth handling and easy ridability. the kawa and the gixxer have a bit more power than the honda though. then the yamaha is now considered under-powered and i heard the front wheel is a lower profile and makes the bike flop into corners.

just a few thoughts, if you're thinking of buying, just read a bunch online and go to a dealership and sit on them all.