The preferred forms of government are pretty irrelevant. It is only that the AI sees you as a little more or a little less favorable if you are in their preferred or shunned government. (Or did you mean something else?)
Maya are good at getting large and developing their land quickly due to the Agricultural and Industrious trait combination. They are only mediocre in other things. For example, they have no UU to speak of and neither are they militaristic, they don't get any scientific or other cultural buildings cheaper or receive any commerce bonuses.
One positive thing about the UU is though, that you can pretty much trigger your Golden Age whenever you want. Of course it might net you one or the other slave too. (And don't forget, Agri also entails that Aqueducts only cost you 50 shields.)