Just trying to keep track of this: what are the forms of government of each of the Nine Free Cities?
Near as I can tell, Braavos is ruled by the "Sealord" but I'm not sure if that's a hereditary title or an elected merchant magister like other Free Cities (sort of like the Doge of Venice).
We know nothing about Lorath.
Volantis is a democracy, well, only the freeborn landholders are allowed to vote for Triarchs, but they have actual elections and political parties (Tigers vs Elephants).
Pentos is ruled by an oligarchy of "forty families", wealthy merchants. Most of the Free Cities are similar to this; rule by wealthy merchant families, sort of like medieval/Renaissance Italian city-states. (I'm not sure if, as a "Magister", Illyrio Mopatis is part of the government or not).
Near as I can tell, all of the other Free Cities basically follow the model of Pentos; ruled by rich merchant oligarchies of Magisters.
Tyrosh's ruler is called an "Archon", but I'm not sure what that means exactly; if its hereditary or just another kind of Magister.
Does anyone else know more about this?