Having owned both, I'll chime in. Let's assume we're talking about '05 or newer.
It really depends on YOU, the rider.
Regular riding around, occassional track day, some posing, etc? Get the CBR. Easier to ride fast and more user-friendly. Honda also has a good reputation for build quality and user-friendliness.
Can't ever get enough power? Find yourself with the throttle twisted all the way to the stop all the time? Track days several times a year, or club-level racing regularly? Wheelie merchant? Get the GSXR.
I have owned more CBR's than GSXRs, but my current ride is a older GSXR 1000 with a turbo system. Two thumbs up.
Looks nearly stock too...
I oftentimes leave a wake of confused squids behind me. :icon_lol:
-Blesum