What is 'is'?

You're killing me man.

Tell me then, what is the best system of government and how you came about that conclusion?

Yes. I'll judge society on common sense, rationality, logic, morality and facts before anything else because there is nothing else.

Systems are products of paradigms. Paradigms are lenses into reality, not reality itself. Systems are the attempt to apply a paradigm.
Since all paradigms suffer from tunnel vision and cognitive bias... no system works.
A system only works in so far as it fits reality. And reality is far more complex than any one lens can fit.

Some lenses just work a bit better than others, bu they will always have limitations, creating a need to continuously switch paradigms.
That is why we always need a "marketplace of ideas". Chances are when a problem really vexes us, we need to look at it in another way.

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"Man lives in the sunlit world of that which he believes to be reality. But unseen by most is an underworld, a place that is just as real... but not as brightly lit... A DARK SIDE!"
-opening from Tales From the Darkside