My current truck is most likely my forever truck as well.
My main reasoning for the Ram/Cummins is the simpler I6 design is bound to have lower operating costs over the long haul, and this theory has a proven track record. The recent fuel economy test towing 22,800 lbs also supports this. The PSD and to a somewhat lesser extent the Duramax are complex animals.
Secondly, I didn't want to be left holding the bag with a failed CP4 high pressure fuel pump and a trashed fuel system. This issue still exists even on late model trucks and I believe it will become a more widespread problem as the trucks age and get more mileage on them.
JMHO and other opinions may vary.