Is one clearly the best?
#11
I think any of the big three will do what you are looking for and with proper care all will last at stock power levels. Go drive all three and which ever one you like you should get. Personally I like the Cummins engine, but the Duramax is nice and the Allison is pretty slick. I'm not really a fan of the fords, I just don't like the looks. As much as I love the cummins I do think I would have to look VERY hard at the duramax if it was gonna be a stock configured tow rig.
And before I forget!
And before I forget!
#16