Great point. I personally wouldn’t be comfortable with monarchy. 

I like the idea of a jurisdiction where there was defense and that’s it. Constitutionally bound defense forces that simply protect and ensure certain rules (eg the constitution) are upheld. Maybe if the defense forces were broken up into many different branches then there would be game theory where they wouldn’t be able to seize power of the territory as the many other branches wouldn’t allow it. And collusion between would be much less likely overall.