The F4 is a great bike. It's more of a neutral sportbike. Good in town, good for cruising, good in corners, etc. The newer 600's all produce pretty good power these days. Myself, I prefer to have strong torque and that's why I love V-Twins. 600's produce itty-bitty torque. The RC51 is a wanna-be Ducati and for a new rider it is a little too "racer-rep".
You need to find out what type of riding you will be doing before you decide on a bike. Honestly though, if you're shopping brand new 600's and if you're not an avid sportbike rider, then the F4 or the Kawasaki ZX6 is probably your ticket. The Yamaha R6 and Suzuki GSXR600 are pure race-reps. Me, I like race-reps since I'm a weekend trackday guy but for a street-only guy they would probably piss you off after a while.