I'm on my 5th Dodge/RAM, 3rd diesel. They have been very good trucks. My '12 just turned 3 years old, and 36000 miles. I do not plan on buying an extended warranty.
I think all 3 of the brands have good diesels right now. Personally, I like everything that is wrapped around the engine as well. If I were buying today, it would be another Dodge/RAM.