My agency's issue gun years ago was a 3". In theory there is no accuracy difference between that and a 4", but practically speaking the 4" is much more forgiving and usually a better pointer as well. It also gives a little more velocity which never hurts. It doesn't matter much for plinking or target shooting but under pressure I would rather run a 4incher. I carried one concealed for most of my career and liked it very much.

A thought: if a 3" is the choice I think the M60 S&W in either .38 Spl. or .357 is a darned good gun and a nice compact package to boot.

They will all do if you do.