I have read four out of the top five, and I have no quarrel with them. I'm a bit surprised that Jonah Goldberg's Liberal Fascism did not make the list. Not that it was flawless, but it made an important point, and it probably out-sold all the panelists' choices put together.
Off the top of my head, here are my top five:
1. Liberal Fascism, by Jonah Goldberg
2. Radicals for Capitalism, by Brian Doherty
3. Myth of the Rational Voter, by Bryan Caplan
4. The Price of Everything, by Russ Roberts
5. The White Man's Burden, by Bill Easterly
If you were to read these five books, you would assimilate a strong case in favor of decentralized markets and considerable skepticism about a powerful state.