Atlas Shrugged should definitely be on the list.
I learned all I needed to know about sexual relationships from Atlas Shrugged.
But, while I like them, they aren't well written. The page after page after page of speeches grind you down. Plus, there is some really twisted personal relationships in her writing that indicate she should have gotten some help.
They are up there, but not the top three. Gibbons Decline and Fall of the Roman Empire and Quo Vadis leave them far behind in the dust.