Both cameras are stellar. For action shooting they are similar enough that other constraints should be introduced to determine which best meets your needs. Given how excellent both are, I would consider ease of use, handling, and similar non-specification factors primarily. When wandering about taking static nature photos, on occasion wildlife wanders (or darts) by me. Being able to quickly change drive, focus mode, etc can be critical. What works best for you may not be what works best for me, so I am not going to give any advice other than try them out or read the manual and see how easy (or annoying and hard) it is to change the settings you care about most on both models.
As far a personal opinion, I prefer the Nikon layout to Canon, but the 1D X is a kickass camera. You really should see how each feels in your hands.
My gripe with the Canon layout was and still is the 4-button in a row layout on the top-right. The light button is waaaayyy over there to the left and the ISO button is a bit cramped in. Still, this may just be my personal preferences and you may love this layout.
The 400/2.8 from both is also kickass.
P.S. Don't feed the troll.