I agree with above post that there is no perfect system and that whether or not a political system works is dependent on the culture that it is meant to govern.
For example, I can't imagine China working as well under a democracy as it does under Communism. Not because of the size of the population (since it seems to work for India), but because of the nature of the people. As a hilarious thought experiment, try to imagine China operating under an electoral college.
That being said, if I had to choose a political system, I would like a democracy operating under a proportional representation system. Upside is that every person's vote counts (as opposed to the necessity for strategic voting). Downside is the increased likelihood of a permanent minority government where nothing gets done.