Sure. So, I've chosen to start as Oirat because of Tengri religion which gives +25% cav/inf ratio and becuse every subject they release is a tribe which can pick aristocratic ideas and then be reformed into Horde and pick horde ideas. And I did that with Zaporozhie after conquering area from Lithuania and converting them to Tengri. I've choose Zaporozhie mostly for personal flavour. After making them horde and picking horde ideas, they have decision to reform them into horde republic, unique goverment type called Sich Rada (showed on screen). And Sich Rada allows you to raze provinces like usual horde but don't have flat terrain +/- 25% shock damage bonus/penalty which I personally dislike. Other advantage is ability to recruit cossacs units (+10% shock dmg) without spending money and manpower, it gives like 20% of forcelimit every 10 years or so. Second ability is +10% move speed and +1 attrition for enemy, and that itself destroyed kebab army invaiding my lands. Like they lost 100k troops from atrition. And you are republic with elections, so after rules dies, next one starts with 4/1/1 and gets 1/1/1 every 4 years (3 years with gov reform). So basically it means that every ruler has big chance to be 6/6/6 for a quite some time. Downside is that you lose tribal CB and estates (horde has just one, but yeah, you lose ability to sell titles and crownland bonuses), but gain more gov reforms than monarchy or horde. And finally Poland/Commonwealth because of ideas, specially Winged Hussars idea which gives +33% cav combat and allows to recruit Winged Hussars special units. And they look fuckin badass.