Comparable are the following:
5D Mark III and 100-400mm would not work for wildlife. So only option with this is adding a 1.4 Extender, but then image quality is expected to be poor.
7D and 100-400mm would result in 640mm though and aperture 5.6, so this is a real option!
And 5D Mark III with 200-400mm/4.0 and 1.4 extender would result in 560mm (which is O.K. for me) and aperture 5.6mm, so this is comparable with option 2. But here I expect superior images over option 2. But high weight and price!!!!