I do not know much about it but it has to do with the leaders' personalities, for those who like to expand a lot(Japan,Germany,Shaka,etc.) they are very likely to pick autocracy,while peaceful ones who keeps only around 5 to 7 cities(on a standard map) will go for freedom(Gandhi,Theresa and so on),order is the most unpredictable one,if you want to see if a leader will choose between order or autocracy,it does't matter the # of cities they have,but rather # of soldiers,on my last playthrough as spain on deity,the Dutch picked autocracy instead of order which really surprised me,but as soon as I find out that they spam the most soldiers it wont be a surprise at all.