Everyone is going to be brand loyal, but I used to have an RV Logistics business and had pickups delivering RV trailers all over Canada from the factories in Indiana. So I was putting on minimum 5500 KM's a week. I had a Dodge 3500 with a Cummins and Ford Superduty's with 6.0 Powerstrokes. All in the 2007 model years. The Cummins was reliable, but I found it harder on fuel than the Ford's and I got sick of the front ends falling out of the Dodge every 50,000 KM.
I preferred the Ford chassis, and if left stock and you GET RID OF the Motorcraft Gold coolant my 6.0 Powerstrokes were trouble free. BUT, as soon as I added a bunch of power to them, they blew head gaskets. My F550 was studded and tuned and no problems other than one time I had it towed because the IPR valve failed.
One negative I have on the older Ford's is their steering system has always been kinda of.......well not the greatest.
But anyway, here's my take on it. The current new pickups have way nicer interiors in them now and I like the newer body styles. But I would take ANY old diesel over the new emission motors.