I believe Communism can be successful, but it never will because of equality reasons, for Communism to exist there would have to no jealousy for other's pay etc. Fascism , I believe would not succeed, it proved to be a mistake in two instances (popular instances). Oligarchy, rule of the rich, well this would succeed if the "elite" knew what they were doing and only seek to benefit the public, but we all know that's not what the "elites" are thinking...money is all they're thinking. I actually believe Monarchy could work, unless of course he was muppeted by the elites thus forming a hidden oligarchy.
I believe Democracy would be a good choice, but limited democracy, such as where the people don't vote for every tiny topic. Limited Democracy would strain less people.