I’d say Ralph in the classic era and Moleman in the post-classic era since Ralph is just a non sequitur machine now. Although when have we last seen Moleman? I don’t recall seeing him in quite some time.
Well between Ralph and the twins I don't think the writers even remember who Hans Moleman is. Really, only recent appearance I remember was Todd, Todd Why Hast Thou Forsaken Me and in that one he nearly kills someone instead.