There aren't a lot of "old" SF shows to really describe as "aging well", there have been a lot more newer SF shows, but out of the meager pickings, I'll give a list: Ill go 20 years and older..pre-1993 in no particular order
1. Twilight Zone: It's the stories that make it, they're still good
2. Outer Limits: It IS becoming more dated all the time, but it's best epiodes are still very good.
3. BSG 1979: They actually didn't use too much that was time period specific, and by comparison, the other big budget SF series of the time was Buck Rogers, which is incredibly dated.
4. STNG: Again, they set it far enough into the future and didn't use a lot of 80s-90s styles that it appears relatively timeless.
5. TOS: Ok yes lots of things ARE dated about it, no question, on the other hand the stories make it a classic, and therefore survive the test of time.
Some of the most dated:
1. Buck Rogers
3. Lost in Space