I used to be a Canon man (EOS5/10/3), but switched to Nikon when I went DSLR.
Both are brilliant, there really is very little to choose between them. If you can, go somewhere where you can hold/ trial/play with both nd see which feels most natural in your hand. See where the buttons fall under your fingers and check out the menu logic to see which suits you best. Also see which camera offers you the best growth potential so as your skills improve it can continue to fulfil your needs (can it support faster battery drive, does it have metal bayonet for more intensive use / pro lenses, which is the most future proofed etc.)
No wrong choice, just ensure it feels right in the hand!