I must say, I was already disappointed by Canon's sample pictures and I was stunned by Nikon's sample pictures.
I know Canon posted pics that were converted raw-to-jpeg in-camera, while Nikon did a raw-to-jpeg conversion probably on a computer. And some people suggested Nikon simply hired a better photographer than Canon. But please, why on earth would Canon post bad samples leading to somewhat incomprehensible justifications?
Also, Canon used some really expensive $10000, and not-yet-released 24-70 II lens for some photos, while Nikon exclusively used regular 14-24, 24-70 or 70-200 lenses that everyone's got.
Why do I feel more comfortable with Nikon when it comes to those two cameras?
By the way, I have neither of the cameras. I have simply been doing my research to figure out which one of them are better for me.
http://web.canon.jp/imaging/eosd/samples/eos5dmk3/
http://imaging.nikon.com/lineup/dslr/d800/sample01.htm