Alex J. Cavanaugh http://alexjcavanaugh.blogspot.com/2010/09/awesome-week.html has a Top Ten Favorite TV Show blog list meme going, here are mine :
The Avengers - the best spy show ever, Steed and his many partners fighting spies and evil masterminds. British tv at it's best.
Doctor Who - the greatest science fiction show ever and the longest running, first saw it in the early 70's when Jon Pertwee was the 3rd Doctor (they're up to Doctor #11).
Hawaii Five-O - the remake starts tonight on CBS, 42 years to the day after the original's pilot was aired. Jack Lord led a crack team of cops fighting crime in paradise. Show lasted 12 years.
Big Bang Theory - My current fave series, the writing and acting are all great and it's funny.
Upstairs Downstairs - British soap set in the early 20th century about the Bellamy family and their servants. I hear Jean Marsh is bringing the series back, she created the original and played Rose.
Addams Family - the family i should have had, wonderful, creepy, ooky...you know the perfect family. The Munsters have aged a bit but the Addams Family is a timeless and very funny comedy based on the Charles Addams cartoons.
The Amazing Race - my favorite "reality" "game" show. The idea of running around the globe for money has always appealed to me (being a semi shut-in).
Mystery Science Theater 3000 - What can i say, one of the few shows that can make me laugh out loud over and over again. Mike or Joel and the bots watching bad movies and making wisecracks...i mean it's like this show was made just for me!
Monty Python's Flying Circus - the series that warped my sense of humour, they are to blame for the smartarse i am today. It's a dead parrot...no it's only stunned...
Have Gun Will Travel - probably the best western ever made for tv. Starring the late great Richard Boone as Paladin. Thoughtful scripts and great acting, a thinking person's western but still with plenty of old west action.
I could go on and on with more great tv shows but only could list 10. I recommend all of these shows and all are on DVD i think.