I recognize that Futurama is quality, but I could never get into it. The jokes are really classy and sophisticated, which is great, but I prefer a more blunt, over the top style.
King of the Hill, I see as more of an "area" piece, where watching it sort of gives you a glimpse into Texan/middle American values. Always enjoyed it for some reason.
Simpsons, is more like Futurama because it's classy and sophisticated. It'll always have a special place in my heart because I grew up in the 90's..
My favorite is definitely South Park. The newer episodes have mostly been crap, but the entire body of work is amazing. I've seen every episode except like two. Amazingly funny, witty, smart, sharp, tackles important issues and has interesting opinions. Not to mention being crude and blunt, which I like. I also think the shows moral conclusions lean libertarian, so I like it in that way