OK, so I had to make it 25 books

In the order in which they were published:

1. G.W.F. Hegel, Philosophy of History
2. Friedrich Nietzsche, The Genealogy of Morals
3. Walter Benjamin, Illuminations
4. George Orwell, Homage to Catalonia
5. Karl Polanyi, The Great Transformation
6. Georges Canguilhem, The Normal and the Pathological
7. Reinhold Niebuhr, The Irony of American History
8. Thomas Kuhn, The Structure of Scientific Revolutions
9. Joan Didion, Slouching Toward Bethlehem
10. Daniel Bell, The Cultural Contradictions of Capitalism
11. Christopher Lasch, Culture of Narcissism
12. Ryszard Kapuściński, Shah of Shahs
13. Stephen J. Gould, The Mismeasure of Man
14. Eric Wolf, Europe and the People without History
15. Marc Reisner, Cadillac Desert
16. Paul Fussell, Class
17. Griel Marcus, Lipstick Traces
18. Donna Haraway, Primate Visions
19. Mike Davis, City of Quartz
20. Frederic Jameson, Postmodernism, or the Cultural Logic of Late Capitalism
21. David Harvey, The Condition of Postmodernity
22. James Ferguson, The Anti-Politics Machine
23. James Scott, Seeing Like a State
24. John Robb, Brave New War
25. Misha Glenny, McMafia

And, if I really had to boil it down to the ten that probably most influence my thinking today (not necessarily the same as the ones who made the biggest impression on me when I read the book), it would probably be Nietzsche, Polanyi, Canguilhem, Kuhn, Bell, Davis, Jameson, Ferguson, Scott, and Robb.