Let's talk about favourite sci-fi shows! Not movies, since there's pretty much of those, but shows, series, whatever it's called...
I'm creating this topic partly because of discussion and partly because I'm looking for recommendations.
Well, for start:
My number 1 is Battlestar Galactica, the new one: It's sci-fi, and yet it feels so realistic, not just characters, but even technology used. IMO it has the best effects to be seen in science fiction ever (I love the shaky cam :D ), it has great characters and never ceases to surprise me. I'm just looking forward till they finish the last season...
Second is FireFly - mostly for the style
The next in list would probably be StarGate - I don't think it's really a good sci-fi, but I have a lots of good memories...
And now, I'm watching first season of Babylon 5 - interesting - I don't think it's somewhat awesome so far, but it's ... interesting.
Star Trek is classic, but, to be honest, I remember only a few parts here and there I caught on TV

Star Trek: TNG is still the best ever.
Firefly: Good enough that I still shed a single emotear when I reminisce about it's unfair cancellation.

Quantum Leap - Awesome
Red Dwarf - Fantastic

Red Dwarf is the best thing ever created for TV.
And then there is Firefly.
BSG is good, but I stopped watching somewhere in 3rd season and dunno if I am ever gonna go back.

Here is my top 3 sci-fi shows:
1) Stargate sg-1
2)Space above and beyond
3)Farscape

I enjoy Star Wars: The Clone Wars | Episodes and also not SCI-FI but I am watching Terminator: The Sarah Connor Chronicles too. Yeah I am fan of Summer Glau (Cameron). This is not the place but I really advice you to watch if you don't one of the Summer Glau's movie called "Serenity".

BSG rules them all for me right now (final episodes coming back Friday! Nerdgasm!)
Both Stargate series come in second (though that could change when the third comes out later this year)
Doctor Who (the new series), can't get enough of it
An honorable mention goes to Amanda Tappings' new series, Sanctuary. It hasn't been on long enough for me to call it an absolute favorite, but I loved the stuff they did this first season with Nicola Tesla, James Watson and Jack the Ripper

I do love BSG, currently my fave. I used to like Stargate, but the later episodes of SG-1 got a little lame and Atlantis never really got my attention. I heard they're coming out with yet ANOTHER Stargate series at some point. Past shows I've loved are Farscape, Red Dwarf as an early teenager (I probably didn't get all the humor, but it was still funny back then), the old Doctor Who's (new ones kinda blow). I never watched Firefly when it was on but I've seen a couple since it ended, along with the movie, and I like it.
I LOVED Quantum Leap as well... I've watched a large portion of the star treks.
I completely forgot about Space: Above and Beyond (thanks Sylian) but I used to love that show as well.
I guess my top three of recent times are:
BSG
Farscape
Stargate SG1

I gotta throw my vote in the Red Dwarf camp. It is the bee's knees. It is the wasp's nipples. It is, I would go so far as to say, the entire set of erogenous zones of every major flying insect of the western world.

Probably only relevant if your'e from the UK - I grew up with Blakes Seven, fantastic show on BBC

Heh, I have books as well, not quite what I've expected though... I'm not saying bad, just ... not what I've expected :D
But yeah, Red Dwarf totally didn't come to my mind, I don't really take it as sci-fi - Truly, that show's great :D

it is scifi.

Not much of a SciFi fan, beyond Star Wars 4-6. There's one series that I have watched over and over again, although it doesn't really qualify as "serious" SF: Tripping the Rift, a CG generated show that mainly pokes fun at Star Trek and Star Wars, but be warned: There are plenty of tasteless, over the top, sexual jokes in there. If you don't like this kind of stuff, then this isn't for you.

Planetes. Great character development, interesting ideas, and realistic "science" part that is shamelessly integrated with "fiction". Very different from everything I've seen, and probably everything you've seen.