I have Canon 400D 7D 5D and can say they are amazing cameras. I think with Canon you will always have better lens choices Than Nikon. its one of those expensive investments you have to take as it cost a lot to change brand.
I see a lot talking about ease of use of camera, I find canon easy to use, its straight forward and logical.
To be honest you can't go wrong with either but for my money Canon has it just for lens range and price.
. oh and I love my 70-200 f2.8 is lens, amazing lens.