Democracy
“Democracy is the worst form of government, except for all the others.” ― Winston S. Churchill
Democracy is the only political system capable of maximizing the sense of freedom and self-determination experienced by the citizens.
Since all of the happiest countries are democracies, and there is no reason to believe that any of the inherently authoritarian alternatives would better serve their citizens in the long run, it's pretty easy to conclude a this point that democracy represents a political best practice.
The structure of democracy can take many forms. Direct, representative, parliamentary, etc.
Voting can also take many forms. First-past-the-post and ranked choice are two options currently being debated in the US, but others exist as well.
Lottery-based representation has also been shown to reduce the drawbacks of self-selecting candidates and self-promoting elections that tend to attract the most narcissistic over the most qualified.
Within the realm of democracy, we can create Evidence-Based Best Practices that demonstrate which representation and voting systems produce the "best" government in terms of various metrics. These might include accurately reflecting the will of the majority, delivering government services efficiently and effectively, or implementing policies that successfully increase Gross National Happiness.