A client friend asked about this, and since it comes up so much, I’ll suggest you click on the ‘Canon Cameras’ in the Categories list and scroll down to the second page to read it all… but here’s my synopsis to get you started:
Now in 2009, it isn’t as critical for a choice between Nikon and Canon… the Nikon is much improved with high ISO, but at the time, I was getting uggo digital noise at 500 ISO with Nikons and Canon was beautiful at 1600-2500ISO in the dark tones, which is critical for me in theatre (I do Geva and Naz Theatre).
I also really felt that Nikon stopped caring about pros. They did a number of totally crappy repairs on my stuff, their rubber body molding would fall off of $5000 cameras and they couldn’t fix it, just stupid cheap stuff (the repair thing was really pointed out to me when an independent repair shop asked me ‘who fixed this last??!… it was so poorly done)
Little things like Canon just shipping me a little missing part as a favor to a pro, etc. made a big difference. Oh, and I don’t know about current cameras, but my Nikons never quite focused right, I was always babying them… and I just took it for granted until using my Canon and I was stunned at my fast, accurate focus.
So, who know’s today, but that was my reasoning 2 years ago before the Nikon D3 came out. And I’m still VERY happy with my cameras. Also now, I have had much fewer repair issues.