Most overrated: Farscape. Okay, maybe this got better after the first season, which was the only one I watched before giving up on the series. The plot was slow and disjointed and I found the main character, John Crichton, to be a jackass. Yet this series seems to have an enthusiastic and sustained fanbase. Why?
Most underrated: Exosquad. This is not the first time that I've extolled the virtues of this early 90s cartoon. And it won't be the last, I assure you. This majestic cartoon with a great story arc was drawn and marketed to appeal to ten year-olds, but written at college level sophistication. It could have only been improved by expansion to a full hour and consistent animation direction.
What say you? What are the most overrated and underrated science fiction television shows?