The 6.7 Cummins in my opinion is the best you can get. I know plenty of people who actually use their trucks the way a truck was originally meant for and by far I see more Cummins driving around then anything else. Downside is it wrapped around FCA garbage so what most people do is just replace worn out/broken parts with quality aftermarket options. That 6.7 just goes and doesn’t stop, it loves to work. 

From my hard core truck guy friends, they LOVE the Cummins diesel.  Built to last.  Built to tow. On the flip side, my Toyota Truck funds aren't too fond of the Chrysler/RAM brand under Fiat.

Good engine!  2019 and 2020 MYs were also offered with the Aisin 6-speed transmission, so overall excellent power train.  However, the other items around it is FCA quality and will not hold up as well as the engine/transmission, esp. the electronics.

I'd get a 5.9 LOL. The new ones are still great engines built to last. The truck surrounding them has deteriorated somewhat, and in the past 7 years or so has had premature serious problems with suspension and other components. If RAM had the build quality of Ford with a Cummins, they would sell a lot more trucks.

The Cummins engine is great but other parts of the vehicle, not so much.