What is the best work of Friedrich Hayek to start with?

[Gio]

I'm particularly interested in his defense of the free market, critiques of Marxism, but I'm also interested in his other work on economics, and any foundation for the above three.

[Michelle B]

Monetary Theory and the Trade Cycle, 1929.
Prices and Production, 1931.
Profits, Interest and Investment: And other essays on the theory of industrial fluctuations, 1939.
The Road to Serfdom, 1944.
Individualism and Economic Order, 1948.
The Counter-revolution of Science: Studies on the Abuse of Reason, 1952.
The Constitution of Liberty, 1960, ...: The Definitive Edition, 2011. Description and preview.
Law, Legislation and Liberty (3 volumes)
Volume I. Rules and Order, 1973.[96]
Volume II. The Mirage of Social Justice, 1976.[97]
Volume III. The Political Order of a Free People, 1979.[98]
The Fatal Conceit: The Errors of Socialism, 1988.