Was this poster written by a federalist or anti-federalist?

It was written by a Federalist

Explanation:

The federalists were a group that advocated for the ratification of the new US Constitution, which established a strong central government, with enough enforcement powers to lead the newly born nation and consisting of three different branches: the judicial, executive and legislative, that could influence and limit the other under the system of Checks and Balances. The poster, then, was most likely written by a Federalist because it lists the main benefits of the new system of government created by the Constitution and encourages the reader to ratify it.

basic principles: federalism, separation of powers, checks and balances, judicial review, representative democracy, limited government, rule of law, individual rights and responsibilities, consent of the governed, majority rule, popular sovereignty, equal protection.