Well, the -4 may be the preferred iteration, but I think all of them are good, given the individual revolver is good. They are well designed, and well made. With the exception of those in the recall (update) range, all should give a life time of service. I have a 586 that I bought when they first camoe on the market that has a lot of rounds through it. It is still is a good shooter, even though it has some blue loss other signs of use. Just check out the gun you are looking at and as long as passes the tests, it should give a lot of satisfaction.