Ford. I have worked on all big 3 diesels, and driven all of them. They all have great drivetrains. However the Ford, hands down, has the best all around package. The body's don't fall apart. I can almost guarantee that there are way more Ford powerstrokes rolling around with 500,000+ miles with the original body and interior still intact. The Duramax and Cummins are up to the task, but not the rest of the truck. This is just my humble opinion, so don't get you panties in a wad if you disagree. The 1999-2003 7.3 Powerstroke Super Duty is probably the best work horse pickup that will ever be built. I have a 2002 F-350 Crew Cab Lariat long box Powerstroke, auto with 275,000 miles, and a 2000 F-250 Extended cab short box Powerstroke with a 6-speed manual with 150,000 miles on it. I plan to own these two trucks the rest of my life, or trade them for other Super Duty 7.3's. They pull anything from loaded stock trailers, to my 35 ft tandem dual flatbed and neither have ever given me problems.