my 04.5 duramax is close to turning 200K with minimal issues. front wheel bearings, which was a known issue that latest bearings fixed. One injector under warranty, other than that pretty reliable.
2015.5 just turned 50K. yes, it had the (in)famous DEF heater failure that the dealer fixed quickly no questioned asked along with a free loaner car. And a onstar module that failed and was replaced under warranty again no issues getting it covered.
I'd buy another in a heartbeat. But IMHO GM, Ford, Dodge are such good rigs that it's more a matter of what YOU like best, not what I like best.