#1 Battlestar Galactica.
#2 Firefly which is tied for
#3 Star Trek TNG
...
#148 Star trek

Star trek tng was awesome... and it ran for a long time, and Firefly was just leaps and bounds better with storyline, and sub-plots. The only reason Firefly isn't clear cut nunber 2 is because it didn't run long enough

BSG is about as good as a sci-fi series can get... ever.