Gas or diesel

To me this completely depends on what your planning to do, how often, and how comfortable you are towing larger trailers. I've had two campers that have had GVWRs of 15,500 and 15,750 respectively that I've towed with an F250 gasser. Neither have bothered me much, matter of fact the last trip was into a 20 mph corning wind and it handled surprisingly well however I think I could actually see the gas gauge moving. Now with this said, my trips are within 2 hours of home and the camper is normally setup on a seasonal lake site so it's truly only a few trips a year and I can usually pick my day to run it down. If I were towing further distance, more often, or in mountainous terrain I would definitely have a 1 ton class SRW Diesel. If the driving conditions included crossing several states and actually doing some cross country touring, it'd be dually. food for thought.