One advantage of democracy is that there is a mechanism for peaceful transition of power if the current leadership isn't working. Without this, a country has to resort to armed rebellion.
China has historically legitimized armed popular rebellion with the concept of the "mandate of heaven". When an armed popular rebellion topples a dynasty, the previous dynasty is said to have lost its mandate of heaven and the successful rebel leader is said to have gained it. This is why China has historically had dynastic cycles. Democracy is a possible solution for escaping the cycle of often disastrous and very bloody armed rebellions.