Lost, Rome, Entourage, The Wire, Curb and Californication are the best recent ones IMO. I used to love 24 as well but I couldn't get into the last season.
Californication is my most recent discovery. It's a Charles Bukowski inspired series about a writer and his problematic life(ex-wife, stagnated career, booze, sex etc). Oh, and you get to see a tit in basically every episode. Lead actor is that guy from the X-Files. They start filming the second season soon.