South Park by far, but I do enjoy Family Guy a lot too.
South Park actually risked completely everything to try and show Muhammad on the show multiple times. For some of you who don't know, Muhammad founded the Islam religion, accepted by Muslims throughout the world as the last of the prophets of God. In the Islamic religion, it is extremely shameful and absolutely forbidden to make and/or show images of Muhammad at all costs. I'm not entirely sure the reason behind it, but that's just the way it is.
South Park had made an episode making fun of every religion's idol, Jesus, Buddha, etc. so, it included Muhammad. Right after, Comedy Central had to either take off that episode completely or censor Muhammad in the episode (which wasn't hard since all Muhammad did was stand in the background). Reason being because the Islamic extremists made death threats against them.
Thus, South Park attempted to show Muhammad again and again in later episodes attempting to make the statement that they do not fear the Islamic extremists and that they should not give into their demands because of fear. Of course, this point was thwarted by Comedy Central because people in power have become terrified of losing their wealth and will not put their fat asses on the line for anything.