The Flat Tax is the only fair tax. Everyone has skin in the game and everyone will pay attention to their own business. You pay 10% (or whatever) and that’s it. That is the very definition of a fair tax.
I would prefer not having any income reported or taxed. A national sales tax would have everyone paying, including the idle rich with their offshore accounts, criminals with their ill-gotten gains, politicians and welfare recipients. In other words, everyone who shops and consumes, which is everyone. That is most fair.