There have been two scifi series that have really redefined the genre in TV terms over the past couple of years. Doctor Who has proved that it can be a mass-market, mainstream hit, topping the viewing figure charts on main national TV stations. 

And Battlestar Galactica has proved that it can be serious, adult drama with as much emotional weight and political focus as any drama produced on either side of the pond. It's a shame that we're only half a season from the final end of the show, but I'd rather it finished well than drifted into cancellation.