Cards on the table: I love all the Star Wars movies, even with all their faults. Why? Lightsabers! Nuff said! Loads of other reasons too, but hey, Lightsabers!
Stargate: Watched them all from the start to finish. In all it's incarnations. Quality Sci Fi all the way. If you don't agree you've probably been spoiled for good sci fi on tv and are getting picky. I can still remember when tv sci fi shows involved characters in silver suits, immense quantities of technobabble and it was against the law to make a sci fi show without a 'cute kid who's a genius and a robot', Star Trek TNG being probably the last show afflicted by this until the law was repealed!
Loved Battlestar (RDM), the final episodes being probably tv sci fi's finest hours IMHO. If you don't agree, then let's take this outside. Be warned, I have a lightsaber!
BSG helped me realise one of the key ingredients of great SF shows for me, I love the fact that all the sweeping epic scenarios, spaceships, battles etc are just setting the scene for the moment when two really great actors come face to face in a scene, and say very little verbally but so much with their body language! Think all the scenes between Edward James Olmos as Adama and Mary McDonnell as Laura Roslin when they were so often on opposite sides of the argument, and yet there was an undeniable frisson between them (they did end up in bed together!). I only wish there had been some confrontational scenes between either Adam and/or Roslin and Dean Stockwell as Cavill (no.1).
Loved season 1 of the Walking Dead, still sticking with Season 2 even though I agree with previous posters that they have been spending a little too much time at the farm, and budget is the obvious reason. The show however is all about the characters so it still sparkles with great scenes between them, Shane being the most interesting at the moment as his character was killed off before this point in the original comic book and therefore he is more of an unknown quantity, and is displaying some worrying tendencies!
Being British, my all time favourite show is Dr Who, a show I have truely grown up with. Along with it's spinoffs, Torchwood and SJA (RIP Liz Sladen, you will always be my no 1 companion!) it really does follow it's own path and isn't just walking in the footsteps of other shows. Also I'm from Gallifrey originally myself so I have a personal connection!
ST:TNG started off being Gene Roddenberry's pure vision. Which is why it got better after others took over the running. Gene god bless him was a little too idealistic about humanity for my taste, he thought we would become angels by the 24th century, and that's not a good recipe for drama. DS9 was much better in that respect and much grittier. It also improved when B5 showed them how it should be done! Voyager started good, had a dodgy first season because they recycled rejected TNG scripts but soon bucked their ideas up. I've been watching re runs lately (up to season 4 and 5 at the momment) and it's getting better all the time. 7 of 9 in a skintight suit? Excuse me while I take another cold shower! She was a great character as well. The Holographic Doctor was a creation of comic genius. As fo the half Klingon Ms Torres, I'm sure I have dated at least one girl who was also half Klingon... I still have the bruises!