Ugh, I can't imagine a more difficult question.
One could say democracy, but democracy is easily dominated by misinformation.
One could say monarchy, but a monarch is easily obsessed with power.
The reason republics seem to work best is because, rather than being one government, it is many, that gives enough room for power shifts to occur. It ASSUMES a pendulum shift rather than resists it. Democracy can overrule totalitarianism, while educated, capable leaders direct the majority of governmental business by their own will.
A pure democracy is, in my opinion, one step away from anarchy. Government seems to be an exercise in restraint. It is built for the purpose of preventing chaos. However, the level of restraint must be monitored, because we value free will.