I much prefer the files too - they have a look that Nikon doesn't.
IMHO, this is the most subjective issue when judging IQ, but also the most important! When you present your images to a client or just a casual observer, they gauge its visual impact based on the overall "look" it conveys, a certain X-factor if you will, not some highly technical method used to calculate DR or noise.
I was reading some review of a crop Nikon body the other day (D7000?) about how its DR put Canon's full-frame bodies to shame in lab tests. This intrigued me, so I checked out some sample images. They weren't bad, but they looked flat and lifeless compared to what I'm accustomed to out of my antiquated 5DC. Sorry, but I'm not buying a camera based on what some lab tests say. I don't know if any tech specs exist that can gauge this sort of thing, but IMHO the film-like color, contrast, sharpness, and overall IQ of bodies like the 5DC, 5DII, and 1DsIII are why LOTS of working pros shoot Canon.
This isn't strictly a Canon vs. Nikon issue either. If lab tests are all that mattered, why would any Canon shooter opt for anything other than a 7D? Doesn't it match the 5DII and 1DsIII in DR for a fraction of the cost? My hunch is that some people just prefer the look of the files produced by the costlier bodies.
The key point for me though is that Canon is a SYSTEM and not a BODY. People crush on bodies too much these days.
Werd. Let's say the D800 is as great as people are making it out to be, and the 5DIII is as bad as people suggest. Many people will just give credit where credit is due, concede that Nikon has won this round, and stick with Canon because it offers a better overall system.