In the 1/2 ton vs 3/4 ton truck debate I don't even consider the 1/2 tons. I want solid axles and decent ground clearance. The pic I posted has the lifted 3/4 ton pushing snow with the bumper... I haven't ever bought a 1/2 truck because if I need a truck, I want a truck, not something designed to make people feel like they are in a car.
The 3/4 ton will be more stable towing partly because of sheer weight. It will have better brakes and suspension for the load.
I would get the F250 gasser over the 6.7 unless the thought of the engine howling up the passes disturbs you. All of the gassers are going to do that. They need rpm to make power. Wont hurt them, it is just different.
I would get the F250 over the F150 for previously mentioned reasons. I would get the 6.4 Ram over any of them, oh wait, I did.
Power Wagon rescues F250 6.7 on forest service road...