Seriously,
Star Trek: Deep Space Nine gets a major vote from me as well, for many reasons mentioned above. I also remember being very amused at the writing contrast between DS9 and Voyager, while they were airing simultaneously. On DS9, Sisko and crew would be changing the very course of the Alpha Quadrant's destiny, with major-budget kick-ass space battles aboard the Defiant, or exploring intense, moving character stories between the conflicted, dynamic cast. Meanwhile on Voyager, Janeway would at best be rehashing some old Star Trek plot about space clouds or fighting off...giant bacteria? No comparison.
I'm glad several other people remember Blake's Seven as well. Avon was one of the greatest anti-heroes ever written in SciFi history, with a wit and style that I've blatantly copied into several villains personalities. And Servalan was just too wicked! I would count the minutes until the end of each episode, wondering how long they could hold off her inevitable "surprise" appearance as the *actual* enemy to be outwitted in the plot. (Though how she could have sneaked around so much in those drag-queen's wet-dream costumes they made here wear all the time is beyond me.)
Less seriously,
Did I actually see Space: 1999 on someone's list?
I do have more fond memories of it than it probably deserves. (I still have my metal Dinkey Toys Eagle transport model up on my shelf, I now notice. And I'm sure I haven't thrown out that Moonbase: Alpha technical manual that I eagerly ordered from Starlog many decades ago.)
OMG! I just had a repressed flashback. The reason I love the D&D Shifter prestige class so much is because of the alien chick that the wandering moonbase picked up in the second (?) season! (Well, that and Odo, of course). What was her name? Maia? All I remember is that she made shapechanging super-cool, and achieved it on screen without a penny of the BBC's limited special effects budget going to waste. All they did was do this super-fast zoom-in shot into one of her eyeballs, and when they pulled back again, presto! It was the eyeball of a hawk, or wolf, or some weird alien tentacled thingy. Way to go, production department! I suppose this alone should get it an honorable mention.