Hmm, I'll play.
1. Buffy - favorite show since the first season. I heart Joss Whedon.
2.Firefly - only one season, but still better than most long-running shows.
3. ER - I love medical dramas, and this is the best one IMO
4. OZ - crazy, gritty, realistic, depressing, horrible...but I could not stop watching.
5. Supernatural - more than two hot brothers. Great writing, and underrated acting.
Notable mentions include Battlestar Galactica, Being Human (original), Freaks and Geeks, Castle, Criminal Minds, Friends, Queer as Folk..and probably some I can't think of right now.
ETA: for those that like Frasier, David Hyde Pierce grew up in the same town as me.