My personal preference from an aesthetic standpoint is the 5'7" bed.
From a utility standpoint, bigger is always better. There's always that situation where you wish you had a bigger bed. For me, 9" of additional space isn't enough added utility to justify. I'd go with 8' if that was available due to plywood and 2x4 sizes.
Maneuverability is also a small factor, though it can't be too much different considering only a ~9" difference in length.
Another factor is my ability to park the truck in the garage. These are nice trucks. If I got a tradesmen, then long bed. A Laramie, Limited or Tungsten? My preference is short bed.
In order of priority, for me:
#1 Aesthetic preference - 5'7"
#2 Able to park in garage - 5'7"
#3 Utility - 8' (if it were available on the trim I wanted)
#4 Maneuverability - 5'7"
There really is no situation where I prefer the 6'4" bed.