You opened a can of worms didn't you?
As a former mechanic who has spend time taking apart and reprogramming the computers and rebuilding the engines on these trucks,I will give you some insight from a different perspective....
Ford: used to make arguably the best diesel ever made, but have not make one comparable since the 7.3L was replaced by the 6.0L. The 6.0 was horrible, the 6.4 better, but still lacked, and the 6.7 again a step forward, but still not as reliable as it should be.
Dodge: The 5.9L was as durable and bulletproof as the 7.3L and is just a near perfect engine. The 6.7L was a pretty decent replacement, but is heavily hindered by the worthless emissions******that they were forced to add. If you remove the DPF and reprogram it accordingly, it becomes the most reliable and powerful diesel ever put into a non-commercial truck.
Chevy: By far the most comfortable ride of the big three. A very capable truck, but not as reliable as the Dodge or Ford. It's all in the tune. The Dodge has the potential to blow the Duramax off the road, but Dodge instead chose to offer a more reliable tune and not force the Cummins to have to work as hard as the Duramax does. The Allison Tranny.... Is not an Allison and falls quite short of what it should (and overheat often).... but still better than Dodge's continual failure to build a reliable high-torque-capable tranny.
I have always hated Chevy diesels, but they are slowly improving as others are slipping. 1995-2003, Ford Ruled with the 7.3L - 2003-2007, Dodge won hands down with the 5.9L. Since 2007 they are all on a more level playing field (partially thanks to EPA standards), but I would have to put Dodge on top for reliable high mileage towing, or Chevy if you want a more comfortable ride and will not be pulling as much weight for too many miles.
Just a last thought, consider a manual transmission for durability or high altitude pulling.