They're both damned good cameras. Anyone who taken a lot of pictures, knows you can't really pick one over the other, or even rationalize why one is better than the other. It's simply a matter of personal preference, and they're both top tier in the DSLR market.

My personal preference is Canon, but only because the user interface doesn't seem quite as friendly comparatively, and it reminds me somewhat of how the Mac OS works. Although I'm sure the Nikon interface is perfectly fine once you get used to it.

I'd really go either way. When I get my next camera, I will be looking at both manufacturers products very closely.