^Wrong on the years.
6.0 was 03-07 in the suoerdutys and the 6.4 was 08-10 but 08 was a late release so more like 2.5 years.
I think the baddest sounding. Diesel pickup is an uncorked 6liter! Sounds like it's gonna inhale you and spit you out!
Bottom line no arguing is even viable on this point. If either engine was worth a chit, they would have not completely changed engine design or mfg after 4 years and 3 years respectively.
That said, there are some crazy power 6 and 6.4 trucks. AND if I was a mechanically inclined kid and wanted a bad @ss HD diesel pickup on an budget, I'd be buying a 6.0 every time! Bulletproof it and have arguable the best chassis and a cool sounding tough truck.
If I wanted down the road gas n go reliability and power, neither of em would make my list!