you now i read alot of these diesel comparison things and really if its a deisel than its good really it don't matter which one you get they all have there ups and downs. the real test is just go out and test drive each kind and you decide which one you like. well hope you decide on a good truck man btw they are all good it just depends on how you drive it.
If the world was the way everyone wanted it. We would all be in gm trucks with a cummins power plant and an allison behind it. I work for gm and love the duramax the 06 with the manule shift 6 speed alison is just as great as you can ask for. Fit and finsh is great. I do have and have owned dodge trucks the cummins is great the trany sucks balls untill u speand another 3000.00 in upgrades to it, there brakes suck if you are pulling. I can and wont comment on the ford I dont know anything about it . The fact is I will never own a ford just me. If I were you drive the truck most new dealers will let you do 24hr drives run the piss out off it. And pick the one that fits your driveing preferance. The warranty on a gm diesle is good so is dodge. Good luck with your dission and what ever your choice make it for yourself not what the mass majority says.
I work in Parts not service not sales I am the middle man in the dealer ship so my thoughts are towards makeing money not saying we make the best truck. Just my 50cents