It depends on the revolver.
If you are looking at a Ruger Super Blackhawk or a Redhawk in .44 Magnum, long 7 1/2"+ barrels make a heavy revolver heavier and are a little awkward for offhand shooting, but offer greater sight radius and long range accuracy for shooting from a rest, or from a sitting position.
For a Ruger Blackhawk, New Vaquero, or Colt SAA Clone, there isn't much difference between a 4 1/2", 4 5/8" or a 5 1/2" barrel, though the shorter barrel is handier. The 7 1/2" barrel is a bit more awkward.
I found the 4 5/8" Blackhawks to be just as accurate as the longer barrel lengths, firing offhand, using either a duelist or two-hand stance.
For .357 DA revolvers, I think that the difference between a 4.2" and a 6" barrel would be also minimal.
Shorter barrel lengths are handier for holster use, if that is a factor.