All the diesel pickups are basically great trucks and all have their weak areas that are well documented and can be fixed.
My own truck is an older Dodge low-mile cream puff with a Cummins and I love it, but I'll tell you up front that it took an expensive ($5500) "built" transmission and a few little other pieces to make it into the reliable powerful truck it is.
The mid-2000s Ford diesels are well known to be a lot of trouble. Even those can be fixed, and they're very nice trucks. In my opinion the biggest "con" with the Ford is the engine is set back so far that the whole truck cab has to be removed from the chassis for most service work. For that reason, the Ford was off my list even though I like them.
My experience with the 2000+ model Chevys is all with gas trucks, but it's all good. They drive great and seem to be extremely reliable. And among the older diesels they probably have the best transmission (Allison). I almost bought one myself (a 25,000 mile '03 dually with a 6.0 gas motor) when I bought the Dodge.
It's too bad the 12-valve Cummins/Dodges are getting so old now (made until 1998) because that IS the best diesel pickup ever made, considering reliability, economy, and power (they're slow if dead-stock but it's super easy to turn them up and they're plenty stout enough to handle that).