The usual conundrum when trying to find a "best" or "worst" ever, most of you don't have the length of experience to try to determine what "ever" means (usually you erroneously apply only the length of your own life).
Swing back young ones. Worst ever TV scifi: "The Starlost"
followed by the Star Wars prequels, or is that second trilogy?
StarLost! Haven't seen you in AGES! Nice to have you back, after the great M6-o-clysm and all.
My personal most-hated sci-fi has to be Armageddon. Most of the others I can let pass to some extent. Let me explain:
Star Wars is not really sci-fi; it's swords-and-wizards fantasy with a sci-fi wrapper. So the prequels, while they do admittedly suck horribly, don't make my list.
Star Trek, original and later alike, has many impossible theories and lousy stories, but it also has many great storylines and lovable characters, and although the physics are too hard to swallow, they are effectively slathered in liberal amounts of handwavium so that you can ignore it and pay attention to the characters. Firefly/Serenity also falls into this category, with a tad less handwavium and way more loveable characters and themes.
I am with Greg Burch about Starship Troopers. The makers of that film should be marched to stand before the tombstone of R. A. Heinlein, forced to apologize, and then executed by making them watch their crappy movie over and over until they expire.
But Armageddon is a special kind of suck.
Prior to the film's release, there was much hype and BS. Smithsonian Air & Space magazine had an article about it, claiming that it had NASA advisors on the set and that it promised to be realistic. This turned out to be BS. In every single space scene there were massively stupid errors too numerous and painful to recount. What killed me most about this is that
it was totally un-necessary! A realistic mission to an approaching asteroid could be planned and done in real life, and there's no reason not to make the movie realistic. Realistic missions can be exciting, see Apollo 13. No handwavium required.
Worse, the story flow, the script, the music, the lousy effects, the cast (is it just me or does the mere presence of Ben Affleck mean the kiss of death for any film?), and the awful music (oops, already said that) add up to a monumentally hateful waste of good camera film. I refuse to ever pay to see another Michael Bay film. Bury his house in physics books and make him read his way back out to daylight, please.