Just as Rich is a Canon guy, I'm Nikon. Why, mainly because I purchased my first Nikon over 20 years ago and started building a system.
I've also used a Canon 1Ds MK III on an assignment and that was also a super bit of kit.
To be honest as Rich also said, both Canon and Nikon produce superb cameras and systems but also don't discount the entry level offerings from Pentax, Olympus, Panasonic, Sony etc.
The only thing I would say about these systems is that whilst they are every bit as good as a Canon or Nikon (certainly in the non-professional areas), the latter two are the only ones I would recommend if you are serious about building a system (lenses, flash, grips, etc) as both Canon and Nikon have by far the most comprehensive systems and support.