Eboz and Hickman might argue with you on that. Though Chip Mayfield road that Yammy and killed us all. Didnt Dale Bouros ( I spelled it wrong) ride a Gxser also? Jammie James was on a Yammy right?
I'd say whatever you are comfortable on. I ride a suzuki 7/11 but the yamaha that Chip rode always had plenty of motor and handled great. Like I said it's probably more about the rider at our level. Lance is fast on anything he throws a leg over no matter what size. Pick one and come on out.
Reason I chose Suzuki is that you can still find parts fairly easily. Several Katana, Bandit parts work for motors and everyone runs an upside down front end.
I would go with the GSXR for the same reasons EBoz gave, but I think I like the Yamaha better. I've never rode the Yamaha, I just like the looks and I'm more of a Yamaha fan than a Suzuki fan. But Kawi's still rule everything!!! Lance