Family guy is for extremely "simple" human beings. Its not funny in the slightest.
I'm not sure I completely agree. Family Guy is a bunch of random clips joined together at random. If you watch them as clips and not in a 30 minute show, some of them are funny. However, if you were to actually sit through 30 minutes of the show, you have to be simple or high.
Simpsons has gotten a lot smarter recently. I don't watch it all the time, but if it's on, I might watch. I was surprised with a few episodes having some more clever word play and references that I don't recall them doing in the past.
South Park and King of The Hill are the only two cartoons I will watch the new episodes that day or the next day online. I think South Park has moments of brilliance and then we have to suffer through duds. King of the Hill was awesome always. Anyone that doesn't like King of the Hill, doesn't like America.