Many questions may be raised when it comes to think of the best mechanism for choosing leaders.
I think that elections , dictatorships, coups, domination of one party power, monarchy, principality and sultanates are not excellent ways to authority for leadership.
Unfortunately, Election sometimes opens up a pandora's box of disasters against voters and even people all over the world. That makes us wondering if there is really democratic states!
As far as I know, in many countries the rate of ignorant electors is bigger than the enlightened electors so the winners will come by the votes of ignorant electors rather than enlightened. Moreover in many cases the will of people in elections would be fabricated by fraud ballot box stuffing. And when the winners come they would stay more presidential terms by changing constitutions in lame excuses. History proves that many leaders had unconstitutional abuse of using power.
We can safely assume that monarchy, principality and sultanates are very often relinquish power according to inheritance, bringing unqualified descendant rulers. And usually loyal families get ill- gotten gains whereas people languish in abject poverty.
In past, the votes of Centre Party and Conservatives in the Reichstag brought Adluf Hitler to seize power in Germany in 1933. So it was as same as the dictatorship which enabled General Franco who lasted for nearly 40 years or brought saddam Hussian in 1979 who lasted 35 years and made Iraq bellwether of the region or as same as coups which brought Idi Amin Dada Oumee, the butcher of Uganda he lasted as the president from 1925 to August 2003.There are many examples like them.
So, to sum it up; all these ways of choosing leaders have significant repercussions. So thinkers should invent a new mechanism for rotation of power to prevent new blood bath.