What form of government best suits the Jewish people? Some folk maintain that we must move with the times and ensure that we adopt to fully democratic model; others hanker for a theocracy, in which the principles of the Torah will provide a framework for all civil and public life. Then there are those who point to the monarchy as being most appropriate, recalling the glory days of David and Solomon and the promise that the sceptre will never leave the Tribe of Yehudah.
The Torah does not specify that we adopt any one form of government to the exclusion of others. Rather, it demands that the interests of truth, justice and peace be placed at the helm of whatever regime we operate. This is made plain by Rabban Shimon ben Gamaliel (Avot 1:18), who identifies truth, justice and peace as the three qualities on which the world depends for its continued existence.
We can conclude that the nature of any system of governance is less important than its functionality: we judge it by its results. If it is fair, respects truth and delivers peace, that is as much as we can hope for. We can also surmise that, if this is the case, even a bad system of governance that is manned by good people will deliver better results than a good system run by bad people.
As for taking up leadership roles, Avot advises avoiding public service and governmental matters if one can (see eg Avot 1:10, 3:6). However, the tractate recognises that someone has to do this work: as Hillel says, "In a place where there are no men, strive to be a man" (Avot 2:6). Public positions cannot be shunned where they leave a leadership vacuum -- and they must be filled even if this means putting aside one's commitment to Torah learning.
