I'd go with the Toureg, or another option not listed... The Volvo XC90. This seems to get good write ups for its off road ability, despite effectively being an 'on-road' $x4 (just like the majority of modern 4x4's)
The Toureg and Cayenne share the same chassis, but just have different running gear on them, so between the two its neither here nor there, it just comes down to the options, as mentioned above!
My friend has a Q7, and loves it, but the most off road they get is the side walk!!
Also maybe consider the Toyota Fortuner?? These have survived the rigors of travelling through most parts of Africa, and parts are in abundance!
Hope that helps some?
G!