I had a diesel X it was a fantastic vehicle however it does not compare to the modern diesels in terms of power and performance. Unless you are full timing and need the passenger space on a full time basis I would opt for a modern diesel pickup.
I also would not avoid DEF it is the pre DEF years that were a bit problematic. There were growing pains to reach the DEF era, but DEF has been reliable.
THe big 3 all currently use DEF with no real issues.
It is the DPF years that suffered with poor fuel mileage and moe emission issues. While not perfect DEF is a vast improvement over what preceded it.
I have a pre emissions Duramax which is a great truck but it does not have the performance of the newer models.