I shoot Pentax and Canon.
Biggest difference to me and other shooters who've shot with Canon and another brand, comparitively, is the RED channel. No kidding.
No matter how I adjust settings, tweak color, custom WB, etc, I can
never get the reds the way I want. I settle. What does this mean in real life? Dark skinned people... don't look
quite like themselves, although the rest of the colors are accurate. Either they have too much RED in their skin, but if you tone it down, everything is washed out a bit. With Pentax, they are considerably closer.