My preferance would be an R6 for 600's and a close call between Gixxer and the Kawi on liter bikes. The Kawis have a monster 1000 cc engine but they may be a lil too hard to drive. This year has seen lots of improvement on the gixxer 1000 which is still very friendly to drive. They have introduced 3 different level of driving conditions switched with the help of a lever near the throttle although i dunno why anybody would use the lowest level, which is basically a gixxer 1000 slower than a 600. The highest level gives maximum gixxer power.Maybe the lever was introduced so that people would buy it not thinking that it may be too fast for them, and whenever they get bored of the slow speed, they can taste the true nature of a litre bike by simply switching the lever.