I personally prefer 5.5" over 4.75" … and in fact, more of my revolvers are 7.5" than either of the shorter lengths … I'm not very fast, anyway, so I go with the look I like!
Somebody mentioned that many Fast Draw competitors prefer the short barrel, and I gather that similar considerations also drive the preference of many Cowboy Mounted Shooting competitors, based on what I was told recently by a chap considering getting into that sport, who passed on a pair of 5.5" Ruger New Vaqueros I am thinking of selling. Calibre (.45 Colt) was right for him, but apparently the advice he is getting is to stick with the shorter barrel (4 ⅝" in the Rugers) for ease of clearing the holster and reholstering while mounted … Of course, in that sport they aren't trying to shoot a bullet accurately … just need to project all that burning powder and fouling in the direction of each balloon ...