Communism

Given the fact that the strongest economic power in the world has been fucking with them for decades, and they still manage to keep up on things like life expectancy and education (at times even surpassing the US on the life expectancy), I'd say they're doing pretty well. And looking at neighboring countries with similar histories that aren't getting fucked by the US, but chose capitalism (or had it chosen for them in case of countries like Chile), I'd say Cuba's a pretty good argument in favor of socialism.