The 01-04 CBR's are no good. Heavy and underperforming even for a 600. Plus if I remember correctly they don't have the cool new honda unilink or whatever it's called, suspension.
The R6 is a great bike no matter what year. BUT if I were you I would go for the 04. It's a solid model year with Fuel Ignition and it's pretty much the best all around bike for the price.
GSXR is always good. On par with performance of the R6 but the 01-04 model years are ugly IMO.
Hands down the R6. Looks great, performs great and it's resale is phenomenal.