I want to see what everyone thinks of the shows/movies below...
Star Trek (from the original series to enterprise and all the movies)
Star Wars ( All six films)
Tough call on a favorite for me... I'll have to think about that. As for my thoughts on each...
Star Trek: I grew up watching the original Trek series (in syndication) and I followed each series and movie without fail (however, I have yet to see the latest movie). Star Trek brought sci-fi into the mainstream laying the ground work for some of the greatest television shows and movies every made, every show/movie on this list was made possible by the original Star Trek series. For the record, I have never dressed up as any character from any Star Trek series (although, I have been know to do the occasional Shatner/Kirk impression).
Star Wars: A saga so intricately told that it took six feature length motion pictures to do so. Where Star Trek broke ground, Star Wars built a thriving metropolis. Story telling that interwove social, political, mythological and theological ideals with a mind blowing visual display of never before seen special effects. I saw the Episode IV (the first movie) at the drive-in on my early teens and was an instant fan.
Stargate: Huge fan of the movie and all three series, I'm really disappointed that NBC/SyFy didn't stand behind SGU and give time to mature. While Stargate doesn't have the same groundbreaking creds of the original Trek and Star Wars, the marriage of extraterrestrials and ancient civilizations was not as widely published at the time of the Stargate movie as it is now.
Starship Troopers: Starship Troopers was neither groundbreaking nor epic, it was however a decent blood and guts adaptation of a mediocre comic book. Let's call it a cult film, not everyone is going to know about it but those that do will defend it vehemently.
Battlestar Galactica: I watched the original television series without fail in my early teens however, I missed out on the SciFi Channel's "reimagined" version. I have seen episodes of the SciFi Channel's version and I'm looking forward to seeing the entire series now that BBC America has obtained the rights to the series. the original series was bold, for it's time, in it's portrayal of human origins. Caprica (a Battlestar spinoff) was another show that NBC/SyFy didn't have the vision to stand behind.