The 5's have it

In the war between Canon and Nikon, this round goes to the former. Canon's latest 5 series is very impressive. In a nutshell, fast autofocus, great ISO performance and very customizable. For example, there are five menus of settings just for autofocus. Haven't had time to do any in depth shooting with it, but here are some samples.

5D Mark III with an adapted Zeiss 21mm

ISO 2500 with no noise reduction