Personally, I wouldn't go gasoline. They don't pull like diesels do, don't get the economy diesels do, and if you trade in your current truck it having a diesel will increase it's value enough to almost offset the premium.
For me, it was the way it pulls. It's such a nicer towing experience.
It's a very personal choice, but for me it's diesel all the way.
2001 HO Cummins powered Dodge 2500
2014 Sierra 346RETS
Nights camped in 2014-28