Every vehicle has the potential to cost you a fortune these days in repairs - gas or diesel. These motorized moving things have become a bit complex. My 2014 seems to be about 60% computer and 40% vehicle.
The maintenance costs between gas and diesel are virtually insignificant IMO. Yes, the diesel will cost you a couple bucks more but when you're dealing with the purchase cost and fuel cost of modern trucks it's pretty much irrelevant. And most calm/logical heads will agree that a diesel a preferred machine for towing.
I've gone from gas to diesel and am now back in gas... mainly because I use my truck 98% of the time as a daily driver. When I'm working less and traveling more I'll likely go back to diesel. To me the purchase would depend on my budget and how I intend to use the vehicle. Don't let the vocal minority scare you away from anything.