The rules might be a dog with fleas, but I have always found the setting for the Rifts RPG to be strangely compelling, mostly in their "everything but the kitchen sink" approach. Actually, I would not be surprised if the Kitchen Sink OCC might be somewhere in the Rifter magazines. The fact that Savage Worlds has somehow managed to pry the Rifts license from Kevin Siembieda's MDC grasp might just be a sign of the Apocalypse.
Close runner up:
Cyberpunk 2020. Take a variety of cyberpunk movies, novels, etc. and frappe' them into a single world that has enough touch points to make fans happy, and you've got Mike Pondsmith's RPG setting. I've read that Pondsmith really wanted an RPG that focused more on character and the pathos of the genre but instead saw the game tack towards the "caper" end of the spectrum (which then informed FASA's Shadowrun). It is a classic case of design intent vs. gamer reality, but the world oozed early 90's cool. I'll freely admit to still owning most of the books for this and have considered running a few sessions for fun, including the outdated technology "of the future."