What is the best sci-fi show of all time?

Babylon 5. It was well-written, well-paced, had a good blend of action, drama, suspense and politics, and is in many ways more relevant today than when it was filmed. I recently watched part of season 1 on Hulu, and while it's a bit dated it's held up really well. Andreas Katsulas, as usual, is brilliant.

Doctor Who. Definitely Doctor Who. I've watched quite a few sci-fi shows in my time, and this one is by far my favorite. The spinoff of the new series of Doctor Who,Torchwood, is also insanely awesome, and worth checking out.

Star Trek Deep Space 9

Doctor Who!

with Star Trek classic and Star Trek next at #2 and 3

Roswell :) but if LOST is sci fi then ABSOLUTELY that because I think it's the best show eveeeer!

Babylon 5, for it's brilliantly fleshed out characters, message of hope and highly entertaining story arc.

It's between Battlestar Galactica, the one that ended last year, and Farscape. And a very close second would be Stargate.

Doctor who

Lost!!!

heroes

smallville