Let's start this by considerations. What are and how were societies formed? As it happened in the pre-historic times we can only speculate and theorize about the "Birth of Society" (and Civilization by inheritance).
Societies appears to be formed by an exchange of services. Raiders who found pretty accommodate to steal now and then weaker tribes, at some point found it to be a way for them to settle too; those weaker tribes would provide them goods paying for protection. Yes folks... at birthplace society and civilization were nothing but protection rackets. So if you happen to be descendant of "great kings" you're saying something as «my ancestor ran a protection racket with loads of thugs»
At some point some lacking arm strength but wanting power came up with a scheme to subdue the strong; Religion.
«-Look, I'm strong!
-But I've a friend that's stronger and loves me much so he will kick your ass if you harass me!
-Where's your friend?
-In «some place you can't go, usually Heaven, but also other places as Mt Olympus», you'll meet him when you die! Ahah! See the thunderbolts? That's my friend farting!»
Roughly however, those scammers managed to create the initial rational society - mind over body ones.
As societies evolved they became more and more rational up to where we stand now and, hopefully, it will continue such evolution process.
Who rules?The ruling power was always addressed to Aristocracy, the ones that are "Aristos" (Ready or apt to rule). An "Aristos" depends on the kind of the society, in a brute force society it means the stronger in a rational social society the most intelligent or the smartest. No other than the "Aristos" will ever possess any power over a society.
The "Struggle of Classes" fallacyThere was no bigger fallacy than invent a conflict where there's none. "Struggles" happens for common goals, classes have different goals therefore they will just "struggle" with their peers, not with other classes. In a way talking about the "struggle of classes" is as ridiculous as to state a game between a basketball and a football team; they both will score at will, once they have totally different goals and see no reason or way to stop the others' intent.
However everybody seeks to know how much the society values his presence and job, so there's a constant "bargain of classes", each one trying to be more valuated, and therefore waged, by the others.
Equilibrium and abuse of powerIf we pick for example Athens and Rome to the end of regent abusive societies and Sparta to the other end, we will notice the principal difference between them was the number of "Aristos". Athens and Rome were rational societies but most of its people were pretty much ignorant, Sparta was a brute force society and most of its people strong, specially because they kill the weak.
In the end Athens and Rome have pretty few people with education enough to be "Aristos", making the rule class a rare material and the ruled as common as bananas, this granted a high value to a cast of despotic rulers. As for Sparta, and since strength ruled on a place where everybody was strong, any abusive king would probably be "packed up to delivery", as there were many people else able for that position.
Just like in a regular market, the more abundant the good the lower the price.
Put this considerations to our daysWe live, at least on the West, in highly rational societies. Everything has to have a reason and coercion is an unacceptable way to make someone abide by certain senseless rule. In this societies the ruler has to be way cult and intelligent, this alone doesn't mean such society isn't up to abuse - if you see Papa Doc on Haiti for an instance, he was cult and intelligent, but ruling over an overall ignorant society which he easily exploited.
The key to prevent abuse in our kind of society is in education, the more educated people you've the more "Aristos" that society have, the more disposable an abusive ruler can be.
"Unfortunately" (for tyrants), "Aristos", being able to rule themselves are way hard to be ruled and demand their representatives to actually represent them instead of just claim to be doing so - as in Communist dictatorships, where the "ruling class claims to be representing the people" when it is indeed representing nobody but itself. So the best ruling model for this society appears to be Democracy.
Democracy as we've it now is becoming however outdated, it has been designed for a World with deadly slow communications. That World is no more! In that past Democracies we've chains of delegations (like the one that elected Bush on his second run for president, even thus he didn't got the majority of the American votes) which are today unacceptable. Yes... in the old days one locally elected member would pick his horse and will go for days until reach the central government where would meet with other representatives elected by their locals to cast the vote... but that was on the old times. Today you can be anywhere in the planet within hours psychically or within seconds virtually.
So it's time to think on push Democracy to more direct levels, more direct representation, without dissolve it into delegations and parties. It wasn't possible up to not so long ago, but now technology and an overall educated population allows it to be true, so we can elect the best without have to elect "the whole packet" that comes along with the party of the one we believe to be the best for the place.