I still own a dodge and I still love them but I cannot, with a clear conscience, recomend a 6.7. Still have nightmares about the down time and money lost with mine. If you want to buy the truck, spent another grand or so removing the dpf and creating a truck that voids the warranty, it's a great vehicle. 6spd trans can't be beat. But......if you want something brand new that will spend very few hours in the shop then the Duramax is your boy.
This is just my .02 and bad experience with the 6.7 so you would probably need to find another opinion.