The 10" of extra wheelbase of the Durango over the Grand Cherokee will give you a much worse breakover angle than any of the Jeeps, even with 2" of "lift" from cranked up torsion bars (and the Durango already starts with 1/2" less ground clearance to start with, compared to the ZJ) Plus, you will end up trading off reliability in the form of stressed CVs, due to the angle you will be putting them at.

If you are just going to run dirt roads and maybe the sand at Glamis or Dumont, I could see the Durango, but if you are doing trails that require a lift, stay away from the Durango for your first off road 4x4.