You may be able to shoot a 6-incher more accurately, but there's nothing inherently more accurate in a 6-inch barrel over a 4-inch. What you do get is a longer sight plane which can help quite a bit when it comes to hitting your target. But the barrel length is not a factor in each guns inherent ability to throw bullets consistently.
I've got 3 six inchers, one 7.5 and one 4 incher. The 6 inch barrels, IMO, look "exactly right" for a revolver, where the 4 looks a bit short. But the 4 incher handles very, very nicely where the 6-inchers seem a bit long at times.
If it's going to be a home defense gun and a toy for the range for the pure enjoyment of shooting, either would be perfectly fine. If you intend to hunt with it, 6-incher is probably a better choice. If you intend to holster carry it for service duty or even utility use in the outdoors, a 4-incher would be more carry friendly.
Seems to me that if you bought one or the other, you'd soon want the other!
