"I find it interesting that you would consider a Ford gasser but not diesel."
6.7 PS is too darn complicated for my liking. Pop the hood and shake my head, same for the GM. Past 100K your repair bill could be very $$$. Of course you could say the same about the Cummins but not nearly as $$$.
GM has dumped the CP4 for a reason. That is why I would place it in MY #2 position. IMHO from what i have read the Ford probably has a better trans than the GM but that is still not enough to put it in my #2.
I have read lots of good about the Ford HD Gasser and now that they have upgraded the whole truck after 19 years on the same platform I would have no issue owning a 17 and newer Ford gasser.