Newer diesel with least problems

Small sample size but so far I have 27k on my 2016 Cummins and have not had to submit any warranty claims yet, truck runs great. A friend of mine had such good luck with his 05 Duramax that he bought a new 2018 one. After 5k miles a push rod cap came loose and his truck has been at the dealer for three weeks while they have his engine apart trying to figure it out.

Best advice I have is to read the forums specific to the engines you are considering to see what the owners are saying and see if you can detect any trends. You always will have a few disgruntled owners but if you get many of them saying the same thing, pay attention...