(still on the air)
Speculative fiction based on theoretical possibilities, and a mad scientist thats both likable and believable, whats not to love? The character and plot development over each season has also been pretty good.
Big Bang Theory
Comedy for geeks and nerds with likeable characters.
Person of Interest
Its a new show, but I really like the idea behind it, and so far the main characters are likable. Its like a good action/adventure movie on a smaller scale with each episode.
The personalities of the the characters and their interaction with each other is what sets this apart from other crime dramas for me.
They keep coming up with interesting ideas to test.
Penn and Teller Tell a Lie
An interesting believe it or not type show. Lots of amazing stuff (most of it real, but one featured item per episode is a lie (they tell you which one at the end).
(not on the air)
Battlestar Galactica (the re-imagined series)
I was a bit disapointed with the ending, but it was an epic story driven drama in a sci-fi setting. The character development and interaction is what sets this apart from other sci-fi series for me.
Game of Thrones
IMO, season 1 has been an excelent translation from book to TV. I'd still recommend reading the book, but I did not feel there were any real glaring ommissions from the books, and it was great to see some of my favorite characters brough to life on TV.
Firefly and Dollhouse are also shows I enjoyed a lot when they were on the air.
(Shows I sometimes watch, mostly in syndication, but sometimes new episodes if the TV is on at the right time)