The most complete revolution, in my opinion, is Argentina.
Does the opponent create Infantry? Mounted Grenadiers and Gatling Guns is the solution.
Does the opponent create Cavalry? Gauchos and Revolutionaries will do the job.
Does the opponent create cannons? Gauchos, mounted Grenadiers and Culebrinas will annihilate their artillery.
Does the opponent have a lot of wall and fortresses? He allows your Mortars and Mounted Grenadiers to raze his structures.
Argentina’s only weakness is its huge dependence on food and the absence of long-term economic improvements.
Also depending on which civilization you use to revolutionize you may have some advantages and disadvantages.
Germans:
The Germans have a good echo thanks to their settler carts, but they lose in population and improvements for the units of Argentina.
Italians:
Italians are a new thing and I haven’t quite mastered them, but they seem like they could be a good option for long-term games.
Spanish:
The Spanish may be the best option, thanks to the haciendas and wonderful years they can have a very strong transition, but they are also the civilization with the most military improvements for Argentina.
There are some guides on revolutions, they are somewhat outdated but I hope they help you.
Despite everything said above, I recommend that you look for the revolution that best suits your game mode.
PS: The Mounted Grenadier is not OP, do not try to use it as the only unit or you will end up losing the food and the game.
