Well, since all attempts of Communism have not gone too well I'm not gonna go with Communism.
Socialism seems like a nice way to get rid of class systems, but at the same time free market is eliminated and laissez faire is basically gone.
Capitalism, which the United States uses (or as close as it can be, there are still some regulations by the government), is nice for freedom of business and market, but it also causes major class divisions.
Probably going to choose Capitalism though just because it allows people to make their own fortunes and hold their own private businesses/land.