12 mp is plenty for almost any usage. In fact for most pro photographers more than 12 mp serves literally no purpose whatsoever. To this majority therefore Nikon provides cameras that have much higher ISO performance, much better A/F and much better ergonomics than Canon, Nikon devastates Canon in performance on it's bodies.
Hyperbole on every point. The D3s has better high ISO (not much better) because it's a newer sensor design than the 5D2. The D700 does not have better high ISO despite being 12 MP.
AF is better on the D700. With Canon you can get a low cost 21 MP FF body, with Nikon you can get low cost pro AF in a FF body. Only their sales departments know which differentiation is better. (That said, I don't understand it when competitors fail to take open shots. Canon should have put pro AF in the 5D2.)
Ergonomics is very much a matter of personal preference. There are things I like and dislike about both.
That said, 12 MP is enough for many uses, so Nikon is not at a huge disadvantage. But there are some popular uses which require more MP. I would rather shoot landscapes with my 7D than with my friend's D700.
Canon's dynamic range and USO are laughable in comparison.
A roughly 1 stop difference on either is not laughable, especially when Nikon has younger sensor designs. Let's see what the differences are with Canon's newest FF sensor.