Get the ZX6R. I rode 600's before getting on an older R1, then after 2 years on the R1, I switched to the '16 ZX10R and I can tell you that even coming from a liter bike, it was a massive difference in power. Also, you'll be used to a bike that LITERALLY goes where you tell it midcorner, the ZX10 isn't like that and if you blow a corner you'll be working hard to pull it back to the apex.
You'll never understand it, until you ride one but please listen to those of use that have been down this path. You'll have SO much fun on a 600 and be safer at the same time. Leave the ZX10 alone for a couple more years.
"Thereís a moment when a rider needs to stop thinking about technology and just twist the throttle."-Pit Beirer, KTM Motor Sport Director