I liked Enterprise! Finally, we had a Star Trek where they weren't bound by the Prime Directive and could bend the rules of ethics a little. This allowed them to explore some ethical issues we never encountered in other Star Trek series (I don't think we've ever seen even Kirk throw a prisoner in an airlock and start bleeding off the atmosphere). That's one of the things that made Firefly or the new Battlestar Galactica so appealing--none of the black-and-white adhering to morals that permeated Star Trek and Star Trek: The Next Generation.
Now, Firefly was a great show that was a ton of fun to watch, but I don't for a minute think that it's destined for greatness. What makes that show shine are two things: the completeness of the universe ('scuse me, I mean, 'Verse) it takes place in and the dialogue between the characters. The plotlines themselves, while they hold up well as capers within the span of a single episode, are really hackneyed and cliched when it comes to the multi-episode arcs. And the characters, individually, separated from all their hilarious dialogue, are all stock characters, and none of them undergoes any character development over the course of the entire series. All of them could be summed up by a single phrase, they act exactly according to how a character with such a summary should act, and we've seen all those characters in other books, movies, and TV shows many times before. Firefly brings this weird mix of extreme imaginitivity and extreme unimaginitivity to the airwaves, which is why it'll always remain a cult thing.
Futurama doesn't fit with the others. It doesn't count.
So, uh...I dunno. I guess I'm not voting. But I threw my two cents out there anyways!