When you have a great king, it's among the best forms of government. The problem is that that great king's successor is probably not also great, and under a bad

When you have a great king, it's among the best forms of government. The problem is that that great king's successor is probably not also great, and under a bad ruler, it's among the worst forms of government, and that bad king can last for your entire lifetime. It's never spectacularly efficient, but the US' form of democracy is meant to be much lower variance. I think it's a good tradeoff.