To this day, I don't think Star Trek: The Original Series and The Twilight Zone have been topped.
Excluding any of the Trek spin-offs, no love for Babylon 5
, Battlestar Galactica Farscape
, or The X-Files
Widening to comedies, I'd also point to Futurama
and Red Dwarf
, although the latter is a British series and out of bounds of the discussion here.