My answer is it depends what's important to you.
The diesel will pull a heavy trailer much better than the rather anemic Chevy 6.0L gasser (it's 50 hp and 50tq behind the competition's gas engines).
The diesel will get better mpg both empty and when towing, but fuel can be more expensive - but this varies.
If any repairs are necessary on the engine, the diesel will be 2-3x what the gas engine will.
Maintenance will be much cheaper on a gas engine truck.
Gas engines do better when used for short trips - especially in colder weather.
The Ram will be worth more when you try to sell or trade it.
The Ram's lower payload due to it being a 2500 isn't all that much of a problem in reality, though it can be on paper.
I'd probably go for the Ram between those two trucks. It's a better value.