Of the four options, the 7D and/or 1D Mark III are your best options. The AF on the 6D and 5D Mark II are good, but not great. If you added the 5D Mark III into the equation, then I would absolutely get that camera.
There is also a pretty good deal ongoing for the 7D body on eBay: http://www.fredmiranda.com/forum/topic/1289670
There is also a pretty good deal ongoing for the 7D body on eBay: http://www.fredmiranda.com/forum/topic/1289670