Nikon

(But thats coming from an old photographer) Either Nikon or Cannon and you will get quality. Among the pros there were two schools, the guys who used Nikon and the ones who wished they had...ok kidding. Really all my years of shooting those were all that pros would consider, unless you can afford Leica, but thats a whole new ball of wax there.
The main reason I went with Nikon over canon, is beacuse at the time I was buying my camera systems, Nikon cameras used all Nikon lenses, and I believe the same is still true today (mind you, that you cant stick an auto focus lens on an old F body and expect it to focus, but the lens will work on the old body.)
Cannon had two lines of lenses the ones that were AF and the ones that weren 't. I have to admint that is still a good reason if its still true (and I dont see how they could have changed two diffrent mounting systems to combine them into one, so its more than likely still true)
Any way either one of those, Nikon or Cannon and you will be happy.