Nikon or Canon if you had to start from scratch?

It depends what point in history you are referring to with this question. Both brands have been top-dog from time to time and based solely on specification, the answer would depend on when the question was asked.

Being a Nikon owner's forum you're not expecting many answers in favour of Canon I hope. Personally I always felt Nikon was superior to Canon and a little more exclusive but if I woke up one day in another dimension in space and time and found I had Canon kit I wouldn't waste too many tears over it.