I feel like Wealth of Nations probably tops Piketty's Capital in the Twenty First Century, as does On the Principles of Political Economy and Taxation by David

I feel like Wealth of Nations probably tops Piketty's Capital in the Twenty First Century, as does On the Principles of Political Economy and Taxation by David Ricardo, The Theory of the Leisure Class: An Economic Study of Institutions by Thorstein Veblin, The Road to Serfdom, Individualism and Economic Order by F.A. Hayek, Human Action by Ludwig von Mises.