i like the GM's (you should really consider one, IMO) and the Fords. a powerstroke is one of the only two fords id ever buy (the other is a lightning ). Sd's look really cool, but so do the chevys. a lot of guys here have superdutys for tow rigs and that they do very well. not sure about how the chevys tow, but i see them used a ton in the oilfield as company trucks so they must do ok too. the newer autos are nice, especially chevys Allison, those are sweet. the 3.73 will get you better gas milage, but im unsure as to how much.
good luck and happy hunting.