I can't say I've been in to sci-fi series since I was a wee lad. Therefore, my favourite series are pretty mainstream. My two favourite ones would have to be Firefly and the recent BSG.
1) Farscape!!! - the best sci-fi show ever, once you get past the first half of Season 1 where they are doing the famaliar normal joe doesn't get alien ways to get you accustomed to the new universe. Once you get to the last 4 episodes of Season 1 you will see why it is the series I have rewatched 5 times over. Just seeing the main protaganist's transformation as a character from start to end is an amazing thing. Thats what I enjoy, every character starts as one thing and through interaction with each other and events, they change who they are. These are as close to living breathing people as you can get on the screen.
2) The Whedonverse (Angel, Buffy, Firefly, Dollhouse) - do I need to explain? (also in that order)
3) Terminator: TSCC - did what I never thought possible, make terminator into a relevant and thought provoking exploration of humanity and how far you would go to protect your family or the world.
4) Battlestar Galatica (all seasons were awesome, period)
5) Stargate Universe
9) Stargate Atlantis
10) The Star Treks (Voyager, DS9, TOS, TNG) - in that order
Yes I love torturted characters (my top 4). Thats why I love Sci-Fi because it allows you to explore characters and situations from much closer than would be normally possible do to the distancing effect of the fanatistical.
I just love serial storytelling and love characters that change throughout the show.
BTW don't know if it counts, since its fantasy, but Once Upon a Time is quickly becoming a new favorite.
Battlestar Galactica ('new' one) is the only one I've watched. Annoyed me a bit as it felt like every second episode was based on a romance.
Seriously? WTH fix your forum code.
(New) Battlestar Galactica, funny enough, i found the seasons 3 & 4 to be most amazing while 1 & 2 were just "nice".
The last two were amazing!
As for my favorite sci-fi series, I'd have to go with Firefly, ofc.
Never really watched much sci fi TV. Though as a kid I did watch a lot of TNG and a seemingly forgotten show called Earth 2. Everyone knows the former but the latter I remember as being very good.
The Venture Bros. - i think it qualifies as a sci-fi. That or Captain Simian and the Space Monkeys - awesome cartoon that can be enjoyed by both kids and adults, and it references plenty of other science fiction films and shows.
Rest of ma favorites are: Firefly, Heroes (too bad it became worse every season), Fringe, and X-files.
Red Dwarf and DS9 tie for first. Dwarf had the comedy, DS9 had the arcs and political intrigue aka The Dominion War.
Third would be Firefly.
I'd say Doctor Who, or at least the one I dislike the least. I find the show to be filled with brilliant actors, good ideas, below average execution, and for the first seasons of the reboot, too much cockney accent that wants me to tear my ears off. I might have liked Rose if it wasn't for that fucking accent. u wot m8
I still wonder who's the fucktard that thought "Hey, let's show how the Weeping Angels move, that'll show the audience what's scary! and HEY, let's make it with shitty CGI too!"
Doctor Who is probably my big one. I've seen all of the New Who series and while it does have its issues, I really enjoy it.
Firefly was awesome, along with Serenity. I really hate that it never had a chance.
Fringe is great, though I haven't been able to catch the latest season. And next season will be the last one. Sad about that.
As for sci-fi anime I would have to go with Cowboy Bebop, because it's one of the best I've seen period.
My favourite is easy; Firefly. Then Farscape (Yay! Insanity! EDIT: Also, my home. I teared up a little because I was feeling very homesick when I watched it).
It's just after that putting them in order gets a little harder. That said, honorable mentions go to Battlestar Galactica (One of the few Sci-Fi series which ended before being canceled) and Stargate: Atlantis (because it managed to keep the fun and adventure from SG:1, that SG:U couldn't, with better production)
Also; I usually use threads like these as a way of discovering new shows. So for anyone who does the same, here's some other Sci-Fi which are, at the very least, interesting.
Caprica - I actually feel like putting this with the honorable mentions, but I've got to no idea why. So it's here. It's a spin-off of Battlestar Galactica, so if you like one watch the other.
Dark Angel - Hit and miss. It had a relatively interesting setting and premise, but the writing wasn't consistent. First season was impressive, second season was painful.
Stargate: SG-1 - It takes awhile for it to find it's feet, but if you can get over that hump it's just fun.
Stargate: Universe - It feels more like Battlestar Galactica than it does Stargate, but it's not bad. It takes itself too seriously though.
Fringe - Worth watching just because of Walter Bishop. Seriously.
Dr Who, I like it so much I own a sonic screwdriver and drove to london to see the Dr Who experience..... Oh yeah, face to face with Daleks!
I'm split between Stargate and The X-Files. Both 90s series which were cancelled. I really liked the main cast of both. They had relatively intelligent, well thought-out plots and sci-fi concepts, and interesting lead characters. Though if I could bring back one, it would be the X-Files, it was peerless in exploring conspiracies in high places and modern day mysteries.
Farscape is something I'd like to try, as is Terminator: SCC.
Farscape is a must see, I recently bought the full 52 disc(I think 52) box set. Watching all of the episodes/extras in HQ is so much better than online.
Other than Farscape I like Firefly, StarTrek TNG and Starhunter at the moment. Can't think of anything else right now.
In no particular Order
Battlestar Galactica (Original and Re-Imagined)
Star Trek (TOS, TNG, DS9 and Voy)
Star Wars: The Clone Wars (Awesome show!)
Babylon 5 ( The greatest Sci-Fi story arc EVER!)
Stargate Universe ( I was seriously pissed off when it was canceled I REALLY loved that show!)
BONUS SECTION!! (Fantasy)
Once Upon A Time
True Blood (mmmmm Jessica!!!)
Game of Thrones
Firefly, Doctor Who or Red Dwarf, depending on what mood I am in at the time
Ity seems I'm in good company here, with my selection as either Battlestar Galactica or Firefly, depending on the mood I'm in.
Farscape is really high up on my list, but that has already been mentioned multiple times, so here's something different:
That show is awesome. It's a bit silly at times, and the second season is a little weaker, but I still love it.
Mobile Suit Gundam(any of the series)
That's all I got.
Dr.Who, Eureka, or Primevil. I was so close to putting Sherlock than I saw the title XD
Babylon 5 with SG-1, Atlantis, BSG and Firefly as runners up!
Firefly, with SG1, Battlestar Galactica and Dr. Who as very close runners up!
FIREFLY MASTER RACE