Personally I would go with Ford. The Superduty front axle is much more stout. Rams have always had weak ball joints, unit bearings, and steering. Also worth noting the wall thickness on the SD Dana 60 is more than the Ram Dana 60. Couple that with the fact that Ford transmissions are much more robust and you will be much better served in the long run with a Ford. Only thing worth noting with Ford is the 6.4L and 6.7L Power Stroke is junk, lots of fuel system issues with no real fix in sight and due to this parts are very hard to come by. But that being said, Ford did just launch the 7.3L gas V-8 wich makes diesel like HP and TQ numbers for $10K less and no weird diesel fuel system and emissions issues...
As far as diesels in general go, due to the emissions required on them and how they work, they simply put are not worth it unless you are constantly under load and running at highway speeds often. The DPFs can be problematic if you run in stop and go a lot or if you have extended idle time. The SCR (the module that utilizes DEF fluid) is problematic because DEF has a crystallization point of about 50*F. This means that a heater must be run even in the warmest climates and once that heater goes out, you get DEF crystallization, poor SCR efficiency and eventually engine de-rate. This issue is exacerbated by low quality DEF.
And naturally someone will inevitably chime in with "Just delete it". I simply cannot stress enough how bad an idea this is. Removing emissions equipment from an engine is a violation of federal law, period. The EPA has shut down all of the legitimate bushiness that were selling and supporting the needed ECM tuning to do this, as such the only people still out there know they are violating federal law and don't care. This often times means customer support is non existent, couple that with the fact that the EPA is now starting to enforce emissions laws on an individual level and you have a recipe for disaster. If you get flagged the best case is you get a few thousand dollar fine, worst case your truck can be confiscated as it is technically an asset being used in the commission of a crime. It may seem like a long shot, and plenty of people don't run into any issues, but in my opinion its not worth it, and I like laying down to sleep at night knowing I'm on the right side of the law...
