Almost 14 years. Doll Man is one of the longer running golden age features. His first appearance in Feature Comics #27 was published in December, 1939. He appeared in every issue through #139 in October, 1949. His own title, Doll Man, ran for 47 issues from Fall 1941 through October, 1953. So that's what, 160 issues total? That's a pretty impressive run, IMHO.
I personally really like the artwork in Quality books. There's the masters, Lou Fine, Will Eisner, Jack Cole, and Reed Crandall of course, but then the second stringers like Al Bryant and Chuck Cuidera are also really good.
As for the Uncle Sam appearances, I don't have any myself, but they're on my wishlist. The National Comics issues with him on the cover are popular right now, which means they're expensive. But if you go after some of Uncle Sam's own series, they're cheaper (except #1) and you get a full book of his stories. (thumbs u