"there is no greater tyranny , than the which is perpetrated under the shield of law and in the name of justice" . based on montesques quote , which form of government would he most likely prefer?

Constitutional Republic.

As for the United States...
A Constitution servers a few purposes. It is the supreme law of the land. No other laws or individuals may supersede the Constitution. All laws that do supersede the Constitution are null, and it is the civic duty of the citizens to disobey and repeal it. All individuals that superseded the Constitution, are criminals.

The Constitution is also a Magna Carta. The Constitution does not limit or restraint at all the governed outside of Natural Law. The Constitution protects the governed and restricts the government to three branches each with limited power. Known as Checks and Balances. 

Montesque would prefer this because under the constitution when tyranny becomes law, rebellion a becomes a duty. 

Answer for apex - the reformation