I don't know if I've ever heard a Sex Pistols song other than "Anarchy in the UK," and that song is shit. The Sex Pistols' "value" is entirely historical, and I don't really care about that. Off the top of my head, I can only think of three Ramones songs ("Rock & Roll High School," "I Wanna Be Sedated" and that "hey ho let's go" song). R&RHS was kind of amusing back in the day, but they're all pretty crappy. Again, more of a historically significant band than one worth listening to.
I guess I'd pick the Ramones if I absolutely had to make a choice, but my real choice is neither.