Darker than Star Trek and it's a whole story with a beginning and an end. For me Sci fi is best when it has a philosophical element asking profound questions within it's narrative. B5 does this admirably.
Battlestar Galactica is good too, the re-imagined one, not the original.
Depending on your preferred genre, whilst joining it with only two seasons to go, Nikita was quite a good watch. For nerdy, military style viewing. Maybe slightly far fetched in patches but still worth investing time into.
Wish i had started from the beginning as i dont now feel compelled to go back and watch from the start as the final series flashed back to lots of the previous happenings.
'I wouldn't say I was the best manager in the business. But I was in the top one.'