I love dystopian fiction.
My favourite classics include 1984, a Canticle for Leibowitz, Fahrenheit 451 and A Clockwork Orange.. I prefer Huxley's Island to Brave New World, though the latter is a Utopian novel (great to read as a pair). And not SF by any means, but still a great dystopian work, Lord of the Flies. Although a short story, also Harrison Bergeron by Kurt Vonnegut. And The Long Walk and Running Man's dystopian themes. My favourite writer overall my be Philip K.Dick, and he has plenty that would appeal to a fan of dystopian fiction -- from him I'll mention Flow My Tears, the Policeman Said.
In terms of fairly recent novels:
Never Let Me Go (brilliant novel, and made into a good film)
The Road (though I'd sooner classify it as post-apocalyptic than dystopian). It had a major effect on me a s father, and it gave me nightmares.
Oryx and Crake (liked the whole trilogy, but that was definitely my favourite of them)
I rather enjoyed Wool and I liked Unwind a lot (often classified a Young Adult novel, but not sure why other than it involves young adults/ kids). Ben Elton's Eden could rather count....