I am told that the Canon vs. Nikon questions are mostly a matter of opinon. The responce is so great for Nikon that I hesitate to say, I have a Conon with a 50mm prime, 15-85mm, and a Tamron 70-300.
I would agree with you. What is better a Chevy or a Ford? The debate can go on forever. Each mfg has it's plus and minus. When I bought my camera I looked at both the Canon and Nikon. Nikon won since it felt better in my hands. I just didn't like how the Canon felt.
That being said I bet once you buy one mfg you stay with them since you have the lenses. Right now I'm looking at upgrading my D80 but it's to a higher end Nikon. I won't even consider Canon since I don't want to start all over with the lens expense.
The main thing is buy what you like and take photos. That's what it's all about. Now days there are enough online reviews for you to do some research before heading to the store.
