If you under warranty, want to mod and like the idea of big power with a tuner and not much else then get a 6.4. If you don't like the idea of something small taking out a $10k motor, high repair out of warranty (higher than the 6.0) and the higer initial purchase price then get a 6.0. The 6.0 has been for the most part figured out. Doing the right things like changing the filters both fuel and oil, adding a coolant filter and deleting the egr and adding studs will give you dang near a bullet proof truck. Added to that the 6.0 can get better mpgs then the 6.4 in most cases and still have plenty of power for what ever you want to do.