Honestly, I'd go with kingship. While Captain Scar made a very good point, monarchy would be a much better way to rule a nation, in my way of thinking.
I especially like the Celtic style of monarchy. When a king dies, the people will mourn him, then the wisest people decide who will replace him, based on wisdom, strength, and overall ability. So that essentially removes (for the most part) the possibility of a corrupt heir.
And if this system were to be founded on God's word, then that means that only the godliest man would be king, thus making a cycle where a king following after God instills wisdom in his people, then, when he dies, the people use that wisdom to select a new king who will follow after God, and continue to instill God's wisdom into the people.
Another thing is that in the Celtic system, the king's word is law. So, if this king were a godly man, that would mean that God's word would be established as law. Not the Old Testament law, mind you. I'm talking about the Law of Grace, which Christ brought, not to overthrow the old law, but to perfect it.
So there's my answer. I hope you enjoyed reading it, even if you disagree with it (which I totally understand). Stay safe, and have a great day!