Democracy/republic. The British monarchy system disgusts me a little. A state should have no business using tax money to prop up and give status to a small group of people just because they were born into a particular family. In an equal society there is no nobility, you should have to earn a status like that.
And anarchy doesn't work either because it fails to get around the ultimate reality that force is sometimes necessary in society, and that's why government has to be there. But I'm opening a can of worms on that one..