Have been the full gambit, diesel, gas, gas, diesel. The Class A 350 Cummins was very quiet, and plenty of torque. Tried the Class C F450, not enough cockpit room, went to a Class A gasser, loved it, spouse did not!
Sound proofing applied but still noisy and engine heat was warm not to mention having to climb over the engine cover, real PIA!! Now have a F250, heavy duty tow package, 5th wheel set up. Have 30,000 lb tow capacity and presently have a 43' WildCat 5er. It pulls great. Love the power and the towing capacity is awesome. Just completed a trip from Dallas to St Louis and averaged 11.8 MPG. Super pleased with that!! Put the cruise control on 65 and it holds speed even going up mild hills without RPM even increasing. Funny thing, looking at F350's and F450's, the rear axle for sure handles more weight but the engine? Same, 6.7L Power Stroke. Now the newer 6.7L do have increased horsepower and torque but manage a little less MPG.
I say, do what ever makes YOU HAPPY!!
Happy Glamping!!!