Canon Canon Canon!!
I have a 1DmkII and 1DmkIIN and strap them to anything L and you will have no probs!
I went through what you are going through about 6 yrs ago. never had any probs with Canon. I have progressed from the D30 to the 10D etc.
As said though, everyone has strong views. I have used a friends Nikon and it is nice. If you are used to Canon then I would stay with it.