David,
I have been shooting with Canon cameras for the past 28 years and love them. I do mostly outdoor shooting and need a camera that is durable and will work in inclimate weather. I also like the battery life of the Canon. I typically shoot anywhere between 400 and 600 images per shoot and have never even had to go to by backup battery. If you get the Nikon and have any fast Canon glass you need to unload, drop me a line.
Joe
Shot with Canon D60 w/ 50mm f/1.4