From its specs and power output compared to other 600 SS of the same year. Take a 2001 R6 for example 15,500 redline around 100HP stock...Put that up against a 2001 F4i 14,200 redline and 92HP.....The F4i is a very reliable bike, a very powerful bike it is not....And that adds to its reliability, lower HP and RPM has a lot to do with that...
Im biased towards Kawaski, so for the street I would say a 636, for the track a 09-12 ZX6R (600)...And I own both currently from brand new a 09 Z6R and a 2013 636 and have ridden both on the street and track
Its hard to choose the right bike for you because really who gets to test ride each brand. I have owned Kawsakis and Yamaha R's, and they both worked well for me, I have ridden GSXR's and CBR's and they just dont fit me as well as the others, but that could be that I am just so used to the ergonomics and engine characteristics of the bikes Ive owned. No matter how good the new GSXR etc is or can be, it just doesnt feel right when I ride it...Its like trying to get me to change helmet brands that I have been wearings for 13 years, it can be the best looking helmet in the world but when I put it on it just doesnt fit right....So I stick with what works for me
Really I dont think you could go wrong with any of them if you give them the time to get used to them