I have had a few 5.9s, auto & manual, and put 110k on a deleted 2012 6.7 cummins
I also have a deleted 17 ford 6.7
Stock for stock the ford runs way better hands down.
I drove a stock 18 3500 cummins and it was much better than my 12, but still not stock ford 6.7
I agree with everything said above on mpg, ease of maint etc.
I hand figure every tank. the dodge was lighter but still got about 3 mpg per tank better unloaded.
The ford's automatic is a beast, always seems to be in the right gear etc. annd i love the manual setting. The ford definitely has more **** crammed in under the hood, but i was pleasantly surprised how easy all the egr parts were to get to. Having just deleted another 18 dodge 6.7 a few weeks ago i would say the ford is actually a little easier just because of that damned back nut on the egr cooler on the cummins, even with a crows foot.
My biggest complaint with the dodge was the 68rfe, even tuned with shift points just the way i wanted it was like it was half retarded sometimes.
I'd say right now dodge is the best bang for your buck, the ford is nicer, more complicated and more expensive.
Either truck will laugh at 8500 lbs, stock or deleted