The next Ryan Holiday-suggested book I read was Twelve Years a Slave by Solomon Northup. I found it similar in many ways to Frederick Douglass's Narrative, and this one was perhaps even more powerful because it was the story of a free man who was kidnapped into slavery and then miraculously rescued. The story was gripping and revealed so much about pre-Civil War society.
I was impressed by how well educated, well spoken, and inventive the author proved to be, creating his own tools, transportation mechanisms, and feeding "technology" when circumstances necessitated it. I also liked the factual tone of the book; the author explicitly says he attempts not to show judgment of his story or the institution of slavery but rather present them how they were and let the reader judge for him or herself.
The ending of the book was the best part in my opinion -- emotional, impactful, and cathartic.