The simple answer is that they all are about the same resolution. No big surprises there. heh.
What is far more important than pixel-peeping and obsessing over small differences that are usually secondary to the quality of the optics(which are often a far more limiting factor at these silly resolutions) is the color balance, issues like fringing, and so on. ie - how it looks versus how razor sharp it is(or isn't) After all, the sensors themselves are the biggest problem and how the cameras deal with the Bayer pattern and so on(actually about a dozen issues besides that) via software and filters and so on are what matters now.
That's easy to tell by just searching online and comparing. http://translate.google.com/translate?u=ht...sl=pl&tl=en
This is the best I can find - the translation is a bit off in places, though.
I personally hate the way the Mamiya looks for this sort of work. YMMV. It's all subjective at this point. The H3 to me looks the best, but the A900 is close behind(author thought the opposite - A900 first, H3 second... OTOH, the Mamiya looks great outdoors.