I have pulled my trailer with 2 tow vehicles... The first was a 2011 Ram 3500 Cummins, the current is a 2013 Duramax 2500 Both were crew cab SRW 4x4s...
Honestly the Cummins felt like it had more power (especially after it ummm, lost its dpf filter) and pulled the trailer easier, but it actually made my wife car sick because the thing rode like an old west wagon. The duramax is MUCH more comfortable to ride in, pulls the trailer fine, just without the snap off the line the Ram had, and (this is real world numbers) gets about 4 mpg better mileage with the trailer and almost 6 mpg better when empty. The duramax feels more "refined" and is no where near as loud. Plus it does not make my wife car sick. :)