Star Trek - The Next Generation
The first 3 seasons were good, but after the fourth it started to get really good, then in the last few seasons you got episodes like "Tapestry" which were wonderfully done.

Star Trek - DS9
Not a fan of all of the episodes, but after the short-lived Klingon/Federation war it started to pick up. Once the Dominion War started the show really started to gain speed. The Dominion War started out a bit lame, then that gritty hand-to-hand combat episode in which Nog lost his leg in battle, the show started to get good. And the big space battles of the 6th and 7th season were nicely done.

BattleStar Galactica
Best Drama on TV. All you got to say about it. I knew it was going to be extra special when:
1) The Pegasus arrived and they didn't copy the original series and blow it up when it first arrived. What happens when you put Lloyd Bridges in charge I guess.
2) They actually did "1 year later" at the end of season 2. You know the show has incredible writers.

And House, Hell's Kitchen, Holmes on Homes Cool