Well, I think I want to add my two pennies worth as well - the best digital camera is not yet invented.
The progress in digital imaging is very fast, the normal lifespan of one model in a store is maybe 9 months, for professional SLR's maybe 12-18months and then they are replaced by something which does more, has more pixels, more automatic, shoots faster etc.
Currently, as of today, I would rate the Canon 1DSMkII and the Nikon D2X as top of the line in the class of "35mm"type cameras. A totally different animal are the pro backs - 22MPx as top of the line, and the results you get with those backs show how far away any DSLR is from the real top of the line.
If money is no issue, try the two mentioned DSLR's and see which one you like more. A full frame sensor is not necessarily a knock-out feature and the math tells you that 12Mpx with a magnification factor of 1,5 equals 18Mpx with a factor of 1. Pixelsize is certainly not uninteresting (noise...) but the gaps between the pixels are also important (fillfactor). If you cannot/don't want to spend that much money, then I would rate the Canon 20D overall better than the same class competition.
So, that's my contribution to this question - George Nyman