Apologies if such a thread already exists; but I didn't see one.
I have just started watching one of my Xmas presents (The Wire, Season One on DVD). 5 episodes in, I'm already convinced it may be one of the best shows I have ever seen. I was curious, what are people's favourite TV shows, and why?
1) Deadwood - I have never been a fan of westerns, but this is well acted, insanely well written, dense, and dark. I love how the political machinations play out, and how the loyalties of the viewer are toyed with as characters change. There was never a weak episode, and it was consistently entertaining.
2) Twin Peaks - For one, it has possibly the greatest character ever, Coop. Also it has an interesting mystery, suburban decay, a massive sense of foreboding, and interestingly quirky characters.
3) Buffy the Vampire Slayer - A great mix of irony and sincerity. Manages to mix monsters and violence with ready with, characters you care about, and interesting storytelling.
4) Veronica Mars - Teen-noir. It had a lot of the brilliant pop culture riffing I loved about Buffy, and genuinely interesting murder mysteries. I also liked the overt class commentary in there.
5) Battlestar Galactica (new series) - a great example of politically charged sci fi. Oddly the religious overtones actually fit it well, and make for a richer show rather than making it cheesy.
Honorable mentions: Gilmore Girls, Carnivale, Firefly, Angel