I would have to say that one of my favorite comedies airing on TV is "It's Always Sunny in Philadelphia." It's definitely in the top 3, and might possibly make my top 10 list of favorite sitcoms of all time.
Let's see if I can quickly sum up the show: three guys, a girl, and Danny DeVito. All of the characters are less than smart, and one or two may actually be borderline retarded. The humor is crude and disrespectful. The storylines are ridiculous. Imagine the best parts of South Park, The Simpsons and Family Guy, but it's live action. Stupid, stupid show with wonderful acting.
And to prove it to you, here's a clip of the opening of the episode from two weeks ago. If you find yourself laughing, please feel free to continue watching the rest of the episode. Kitten Mittens. C'mon.
If comedy isn't your thing and you need a good drama with some excellent anti-heroes, I highly recommend "Sons of Anarchy." It might actually be better than "The Shield," and that show was awesome.