I own both cameras, each has it special place. For low light level and small file size I used the D3. For landscape and large file panoramas, I used the 1DS MkIII. If you going to just get one, try it out and see what works for you. I really don't care, if it is a Nikon or Canon, what I do care is what works for me. (in fact, my D3 has the Canon strap and my Canon has the D3 strap)