I stick with Nikon. I have never been disappointed so far and I am still very very very happy with my now obsolete Nikon D700 (now superseded replaced by the new D800 but not replaced!).
First of all, I like the dials and buttons layout of Nikon. I can change most of the functions with just one hand and in complete darkness or without the needs of taking my eyes off the view finder.
Second, it allows me to use the old (AI and beyond) Nikon lenses I’ve invested previously! They all work! For a long time Nikon has insisted that all future camera bodies must be able to use lenses manufactured before. This has caused Nikon to lose out to Canon in terms of frequency of updates of their camera bodies. But this vision has paid off for Nikon.
Third, Nikon only have a single range of lenses for both professionals and amateurs. Unlike Canon which segments their lenses so aggressively that it has become a chore for amateurs to migrate towards professional territory.
Fourth, the skin tone reproduction of Nikon really trash the competition. You do not need special calibration or white balance tweaking to get a natural looking skin tone. Pick up any Nikon and shoot is all you need.
Fifth, the flash system of Nikon is space edge technology compared to the rest. The balance TTL is so idiot proof. Mount the flash and shoot. It is so good that without needing additional tool or upgrade (except for a tripod and a brolly) my SB-800 can double as a portable strobe light!
Someone may tell you that Canon has faster focusing lens speed than Nikon. That was in the past. Nikon wanted their new bodies to be still compatible with older lenses, which were driven by the screw motor built into the body. For a decade or so, Nikon lost out big time in focusing speed to Canon because Canon made do with their body driven focusing motor and built the focusing motors into the lenses.
Today, Nikon has Silent Wave focusing motor built into their lenses, while still retaining the body mounted screw focusing motor! Therefore you can still use the older (AI and newer) lenses and enjoy the newer faster lenses. Don’t worry, non AI lenses were pre 1980s.
Nevertheless, no matter what brand you choose in your final decision, the most important thing to remember is to enjoy photography!