Colt Pythons are pretty and have great reputations but are probably over rated. I have never handled a Ruger GP-100 but I do have an old Ruger Security Six (2.5") and a Ruger Service Six (4"). I shoot both very well (as a Model 10 fan, and Vaquero fan, the Security Six fixed sights are just fine). Neither is gorgeous but I did jazz up the snubbie. I have actually carried this gun with those stocks on it. I know it sounds weird to put Hogue Target stocks on a snub gun like this but I hated the originals.
I have had both guns for so long I can't recall when I got them!
Anyway, I like S&Ws better and I don't think a Python is better looking than a 4" Model 19, among others.