New tow vehicle...6.4 hemi or Diesel?

I have a 2003 2500 with the 5.7. It has served me well and still does a fine job. But the heaviest thing I tow is an a body or my little 28 horsepower tractor. I thought about upgrading and last year rented a 2500 with the Cummins to tow my car to Carlisle to check it out. Nice truck, did a great job. Almost too much truck for one little a body. And the def is a pain in the ***. 12000 lb? Towing all the time? Probably the diesel.