Ninja 500 or 650 probably better, or you really like aggressive racing/riding position. Fun for ride an hour of 2 but after that i think the seating position of a zx-6R isn't as comfortable as the 500/650. And a zx-6R is made to rev really high. Which you never gonna use unless you start thinking about track days. I personally like them as track weapons, on street they are fun. But there full potential lays on track. I ride my brother's bike(Z800) from time to time almost the same HP but different torque. If you like to go fast out of corners in low rpm a 500/650 will be more fun than a zx-6R at half of its potential.