Of the ones that have been mentioned so far:
Starcops sounds very interesting, it's probably less well known. IT's something I would definitely want to watch. Only season 1 seems to be available on youtube.
Blake's 7 - I've only watched it through once and really enjoyed it. This would probably be one for the "do one season, vote to continue" idea to work with. Amazingly all 4 seasons appear to be on youtube.
Space 1999 - Another show I've been meaning to get round to. I watched an episode the other day and it's got a regular assignment for Rollin Hand
So that's always a big plus in my book.
Looking on youtube there doesn't appear to be a complete series for this.
Finally the Omega Factor, it was on my list to suggest before Twin Peaks. I can't remember if I did. A great show and not too many episodes.
Appears to be all up on youtube as well.
My guess would be it will come down to Blake's 7 or StarCops. At a glance Blake's 7 seems popular.
The voting process I took part in last time seemed to work well.