first recommendation: "pre-safety" Three Screw Ruger Single Action Six, with extra 22 mag cylinder
second recommendation: "modern" Two Screw Ruger Single Action Six, with 22 mag cylinder
my "three screw" model is now easily worth $500+, but I still have the original box with SN marked on it with aluminum grease marker, the warranty card, all original hardware, the spare cylinder red bag with gold cord, and the original price tag on the string that was hanging from the trigger guard marked "$69.95"
My Dad bought it for us in '71 or '72 and he probably didn't shoot more than a couple hundred rounds through it. Since he died a few years ago, the only time the gun comes out is for my grandson to run a few rounds through.
Rugers are rock solid and definately have the potential to be passed down a generation or three