I was a big fan of The X-Files when it went on the air in 1993. I'm not a fan of science fiction, but I appreciated the premise -- rare for a tv show -- that the two main characters, a man and a woman, could work together as equals without the usual "will they or won't they" love-interest storyline. Credit Chris Carter, the show's creator and main writer, for that. Dana Scully (played by Gillian Anderson), probably the more complex of the two leads, was smart, strong, ambitious, independent, reserved, and caring. She and her partner, Fox Mulder (David Duchovny), treated each other with respect, and as they continued to work together, they developed a strong sense of loyalty to each other (and, granted, you did hope that they would get together).
I was less interested in the running story about a government conspiracy and an alien settlement on earth than I was in the individual stories and how Mulder and Scully dealt with the situations and with each other. I stopped watching about four years into the show, after I moved to a new city and gave up my VCR. The show ran for nine seasons, and Time magazine named it among the 100 best television shows of all-time.
I also liked that Mulder was the "believer" and Scully the skeptic. She was a medical doctor and grounded in science; Mulder was a criminal profiler and went on intuition. This, too, played counter to the usual boy-girl scenarios and stereotypes. When Scully became convinced that Mulder was right, we, as her surrogates, believed it too.
A couple of months ago I discovered that the SciFi Channel was re-running the series. I started Tivo-ing the episodes I hadn't seen, and stacking them up for later viewing. Every once in a while I watch one, and it's a treat. Most episodes were very dark, but once in a while Chris Carter, with a big wink, would throw in a comic episode: Mulder and Scully spend Christmas Eve in a haunted house with ghosts; an obnoxious guy takes over Mulder's body and comes on to Scully, and "Mulder" plays the De Niro "you talkin to me?" scene from Taxi Driver in front of his mirror.
All in all, for a show about aliens, conspiracies, and UFOs, it was remarkably grown-up.