What was the most significant argument of the anti federalists?

The opposition to federalism had several axes, such as opposition to the constitution, since it was thought that the strong power of the national government could mean a threat to the sovereignty of states, localities and individuals, which could be interpreted as an attempt to disguise a "monarchical" power. Some antifederalists thought that the articles of the confederation gave quite enough power to the central government, while others considered that, although the national government with the articles wasn't that strong, with the Constitution it would be too powerful.