I'm not on any camera company's payroll and don't automatically think that what I'm shooting is the best, just because I'm using it.
Even though I shot film Nikons for a couple of decades, when I finally decided to take the plung into digital, it seemed to me that Nikon had priced themselves out of the market share and that Canon had taken over. So my choice was between Pentax and Canon.
I went with Pentax, because it seemed to be the best deal for the money. I shoot a K20D (14.6 mp), and I'm pretty happy with it, and expecially with Pentax DA* and Limited glass. But sensor size also factors into it.
I'm not sure about Nikon, but I believe theirs is a full frame sensor, like Canon, while mine is a bit smaller, and the way I've come to understand it, the larger size sensor makes better use of the megapixels, just as a medium format made better use of film than did 35mm. That may not be a good comparison, but in principle, I believe it is correct.
So, the way I understand it, that would make Nikon's 12 mp camera with a full range sensor very near the image capturing quality of my Pentax 14.6.
What is seldom considered in these type of camera discussions is the quality of the glass you put in front of the sensor. All the talk is about bodies. But a cheap lens in front of 24 mp probably would not give one better results than a great lens in front of a 12 mp camera.
There were a few reasons I went with Pentax, but one of the biggest was that Pentax, I think, offers prime lenses with a quality unsurpassed this side of Zeiss. For picture quality, I think the glass the image passes through is more important than all the bells and whistles that control it, and maybe even the megapixels it lands upon.