Just finished them instead of reading them right now, but "The Left Hand of Darkness" and "The Dispossessed" by Ursula K. Le Guin. I liked the world building of the first far better, but it didn't hit at the politics I wanted to read about as much as I wanted, the second being the opposite.

I don't know why, but I just need content wrapped in sci-fi for me to find it enjoyable, and "The Dispossessed" in particular was what I was looking for, an exploration of anarchism grounded in examples and thought experiment.

Both of them are fantastic books, and definitely worth a read for anybody interested in science fiction, sexuality & gender, and anarchism.