Pirelli Diablo Corsas or Dunlop D208RR are IMHO the best ones at the mo. HTH.
Don't like Michelin (although i'm french ) because i find them too long to get in temperature, and are VERY slippy when cold (especially if you have loads of low end torque). This is my own opinion tho, and caused me bad surprises from time to time on track when they were cold because of the HUGE torque my Ducati's have, but you may not notice it on a 600.