I'm not a big fan of those engines they've had problems over the years. Especially if you're caring and heavy weights or towing

The pentastar had some issues early, but by the years you are looking it was pretty solid.  Simple, reasonably reliable, easy to work on, and relatively inexpensive to repair and maintain.  For both the engines you mention, they continue the general theme that Chrysler has made strong engines with a weak supporting cast.  Those trucks are known for having a hundred little electrical gremlins, even though the engine itself doesn't cause too many problems.

The 5.7 Hemi is the same song with 2 more cylinders; great engine, weak electricals.  Which is better depends on your use.  For light loads and longer commutes, the 6 cylinder will be fine and certainly save you gas.  Heavier loads and shorter commutes favor the 5.7.  If you're on the fence, get the Hemi; the day is coming soon when a half-ton pickup with a naturally aspirated V8 will be worth it's weight in gold.