If you have plenty of $$$, then use Leica on Canon (or is it Carl Zeiss?), or customise-build your own lenses. Then in that scenerio, Canon lenses no good lor...
I am a Nikon convert. To me, both Nikon and Canon lenses are sharp enough for me. If you are talking superly sharp, like katana standard, then I dare not guarantee.
For general purpose, like me to take family photos, and the occassional school event and wedding, it good enough for me.
so sharp it'll cut ur CMOS in half! =P
u could always go for the third party Sigma 70-200 f2.8. i believe that it's cheaper than even the Canon 70-200 f4 (please correct me if i am wrong here)