Originally Posted by The1
I think your best bet since you say wildlife would be to aim for the 7D, it has a much faster auto focus then anything else you listed, and it's also sharper then the 5D mk II when cropped to 100%, so even if you're shooting off into the distance, you can zoom in a ton and nobody would know it was a crop. Yes the 5D mk II is good for that too, but you'd only want to crop to about 95% of the zoom since after that, things start to get a bit soft.
I have both cameras and have played with this crop ratio, and it's interesting to see the difference. That being said, if you're shooting wildlife in the woods or something and you need to use an ISO higher then about 640, then the 5D mk II might be the better option for you, although you sacrifice the faster focus.
and let's not forget, the 7D is a whole lot cheaper
I've tossed all those thoughts around in my head
and I've come up with the next body will be the 7D for AF or 5D II/III for low light/landscape. I will typically only do landscape or wildlife/planes. IQ and AF are very high on my list of needs, along with more pixels on the screen to check focus. The 240k on the 40D sucks big time.