A Clockwork Orange
The first time I read ACO, back in high school, I struggled for the first third (just about wore myself out flipping back and forth between the text and glossery), but the it clicked and I just sank into the language. That's still the main pleasure here - I mean, the story is well worth it, but Alex's rolling nadsat places a layer of beauty over the rape and ultraviolence. Without that, Burgess would have had a hell of a time getting any sympathy for his hooligans.
I could sit and discuss ACO for hours, but I also feel like pretty much everything's been said. Which is more desirable - the evil of the individual or the control of the state? I imagine your opinion depends on whether you're putting in the boot or catching it in the yarbles.
As a side note, some of the my favorite oi songs reference ACO, but I suspect that lingering association has more to do with the Kubrick vision than simply the novel. The book (1962) predates the rise of the skins and punks by a good 5 or 7 years, but the movie (1971) was made right when gangs of skinhead yobs stomped around much of urban England. Their image and nonpolitical violence drips from every frame.
final thought: You don't have to love it, but it probably ought to read it.