I loved Buffy and Angel, though I hope those do not count as old shows yet. Xena was definitely awesome, and the Beauty and the Beast series. I always have enjoyed Stargate, though I hope that doesn't count as old yet.. <.<
As cheesy as some might find these shows, I love comics, so I was recently watching some episodes of the old Wonder Woman show with Linda Carter. Dark Shadows, and others mentioned I love as well. A-team, MacGuyver, and well, I just thought of two kid shows that I vaguely recall .. "The Tomorrow People" and "You can't do that on television" on Nickelodeon I think it was. Oh, and I love Doctor Who.