This is kind of like comparing boxers VS the tighty whiteys. Only YOU can decide. You need to evaluate what you're going to do with it, and go from there. I will say the the 6.7 is a dog, and you couldn't give me one. It's not just the Dodge, all of the newer EPA'd to death oil burners are having the issue. The earlier 5.9's do have thier issues, but still a damn good engine.
The diesel VS gas thing is simple. The diesel, any of the big three, will be going strong at 250K miles. If you keep your junk that long, the diesel may be the way to go. Personally, I won't keep a truck that long because the rest of the vehicle is falling apart anyway. As far as towing, hands down the oil burner as well. Fuel mileage to me is a wash, and I've had plenty of both to compare. What you lose in MPG on the gasser just offsets the higher initial cost to buy the truck, and the higher routine maintenance cost. For a daily driver/short commuter, my choice will always be a gas engine.
Oh, on the newer Dodge look at the front end VERY close. The newer Cummins have a major issue with death wobble (I haven't heard of any gassers having it). There is a factory update available. You can see it very easily by the monster tie rod and such that they install. They won't come out and say it's is an issue, but if you complain about the wobble they will install the upgrade. Most dealers will charge you for the re-alignment though.