I can't really pick a top 5 'cause I enjoy such a variety, but my favourites include...
Everwood: The script and the acting in this series is incredible. The comedy and tragedy are well balanced (both in and of themselves and against one another), and it manages to avoid being ridiculous. The series touches upon real life and the nature of real people. I can't recommend this enough.
House: Hugh Laurie makes this series!

It's been a while since I watched an episode, but I remember it being well written, tense, funny (at times), and intriguing.
Desperate Housewives: This would be a guilty pleasure... Sadly, the drama in series 6 and 7 is a little too extreme, but series 1 - 5 are clever.
Moomin: I used to watch this all the time as a kid! Now I have a few of the DVDs. It's extremely quirky, and the voices grate on the ears, but the concept, characters, and the stories are incredibly charming.
Animals of Farthing Wood: Another TV series I used to watch as a kid, now on DVD. This one's more dark (save for the third series). It's obviously an adaptation of the books by Colin Dann, and thus follows a good story with well composed characters. The arty style of series 1 is pretty nice to watch, too.
Also very fond of The Simpsons, American Dad, Black Books, Black Adder, and Charmed