I would argue Wild, Wild West counts as Spy-fi, not sci-fi. Other Spy-fi shows include:
Mission: Impossible
The Man (Woman, Third-cousin) from U.N.C.L.E.
Get Smart
Alias
Possibly "I Spy" and "The Avengers" are included, though I've never actually watched them.
If I had to add shows to the top 50 list, they would include DS9, Red Dwarf, Farscape, SeaQuest DSV, The Outer Limits, Space: Above and Beyond, and The Invaders.
BTW: tv.com lists their top rated (9.0 or 9.1 out of 10) sci-fi shows as:
Firefly
Buffy the Vampire Slayer
Stargate SG-1
The X-Files
Farscape
Battlestar Galactica (new)
Stargate Atlantis
Star Trek: The Next Generation
The Twilight Zone
Babylon 5
Doctor Who