The Enclave.
Though, I wouldn't allow it to be the way that it is at the moment. It was first run by an idiot president and then a flipping southern-accented computer-politician. Since the Enclave was suppose to be the shadow of American government and the builders of the Vaults, I suppose that makes sense, but they are an evil organization based in military power, so my joining these ranks would be as one who ascends to the top as its master, a proper madman on the throne, so to speak. I would be Number One...