His essays Shooting An Elephant and Politics and the English Language have always stuck with me. We have the 4 volume collection in the family. It's at an arm's distance right now.
I read Animal Farm when I was 12 and 1984 a few years later. And I've re-read them a few times since. In college, I read Down and Out. Traveling through Europe I read Homage to Catalonia.
Orwell is my favorite writer and 1984 is my favorite book.