When I got into photography back in the film days I wanted a Nikon because everybody I shot with had one. When I went to the camera store and tried out the cameras I liked the way the Nikons felt, sturdy and solid in the hand. I liked how fast their autofocus was compared to Canon's and how it just snapped into focus. But when it came down to which one to buy I got a lot more bang for my buck going the Canon route. Comparable Canon bodies and lenses were a lot cheaper.
When it was time to upgrade I went through the same process, had the same experience but ended up with the same conclusion and sticking with Canon. Now, I've got so much invested in L glass and high end bodies I'm married to the system and won't change.
The interesting thing now is that with the new generation of Canon bodies and lenses that have been announced they are priced considerably more than their Nikon equivalent. It's interesting how that aspect has changed. While I never cared a lot about all the buttons, switches and dials that littered the Nikon bodies it's interesting to notice how the Nikons (ie, D4, D800) are becoming more like Canon. It seems that they have removed some of the dials and switches and replaced them with buttons and menu selections.
Anyway, the bottom line is that I'm happy with my Canon cameras and lenses. And that's what counts isn't it?