Government is not a one-size-fits-all entity. There is not, has not, and will not ever be one type of government that works for everyone. And it's not so much about those governed as about those who create the government. The ones who are governed are typically content--when they aren't they help some other group overthrow the current system. But not to put themselves in charge--that's too much work! But to put those who prefer running things a different way in the position of governing them. Every successful empire let local governors run things in a manner comfortable for those governing and tolerable to those governed.

Additionally, the larger the governing organization, the greater the threat of in-fighting and fragmentation. There is a stabilizing point at which a government is capable of maintaining its various parts. Too small and they are absorbed by another entity. Too large and they collapse. European countries are an example of the former... they are now reconfiguring as the EU which claims to be non-governmental, but its more like the early US. The latter type is China which is suffering from political bloat. Sooner or later China will regurgitate smaller governments and eventually explode into independent units (which then may be absorbed by other governments).

The US is somewhere in the middle, leaning towards the bloating phase. The technocultural revolutions of the 20th and 21st centuries are hastening it's demise. The governmental system was not built to endure the types of changes in recent and current generations.

Finally, someone may determine the "best" form of government in an ideological respect, but human nature, culture, and economics will find any ideal to be unsustainable in the real world.