I have shot both, switched from Canon to Nikon, I'll sum this up so that no more posts need to be made.
Lenses are equal in quality and selection except for....... Nikon has the 14-24 legend, Canon is coming out with a competitor but from what I've seen it is ridiculously expensive and no word on whether it can match the legend. Canon has better tilt shift options.
Ergonomics, very close, a matter of personal preference.
Some claim one AF system is better than the other, I have found that both are good and it has more to do with experience and how you use them.
Canon live view is way better.
Nikon sensors destroy canon sensors at this time. Period.
Sony has good sensors, but the lens selection is weak, and you will often find that sony users have a pathological hatred for Nikon. This is caused by extreme bitterness and jealousy.