Which amendment was the most important to the anti-federalists? why?

According to Google, the most important amendment was the tenth amendment to the Anti-Federalist. Whereby, it gave the States the power to hold all powers not listed in the Constitution. Just remember though that the debate is that all
the amendments in the Bill of Rights are vital to ensure everyone in America with Life, Library, and Pursuit of Happiness.

Decontamination of materials.