Ubik by Philip K. Dick (it's hard to cherry pick his best work though, ask me a different day and I will choose The Three Stigmata or Do Androids Dream or something else)
The Stars My Destination by Alfred Bester (simply a good story and a great background)
1984 by George Orwell.
What all these books share is the idea that sci-fi is about social, cultural and economic dynamics, not ships or time travel.
That is my definition of sci-fi: An on-going essay about the evolution of the dynamics of society, using exotic technology/science merely as a catalyst.
Runner up: Ender's Game by Orson Scott Card
Could never finish (can't recommend): - Neuromancer - Cryptonomicon (Does the author feel entitled to mock the homosexuality of Alan Turing? Found that somewhat arrogant and in bad taste.)
Try as I might, I can't remember any mocking of Turing in the Cryptonomicon. I'm quite confident Neal Stephenson is not a homophobe.
Alfred Bester's _The Stars My Destination_: It's deeply flawed, wackily 1950s, has ridiculous tech, and is one of the most entertaining books I have read.
Stanislaw Lem's _Solaris_: Strange, dry, bordering on boring, breaks every single law about overusing exposition I can think of...and somehow turns that into a riveting meditation on the nature of guilt and consciousness.
Because 'unix epoch' is why. Also: it feels like a future where the details are right, but largely hidden unless needed.
Star Fraction, Ken MacLeod.
A romping good read, is why.
For me I don't have a one favorite book, but my take would be:
- 1984 from Orwell
- the Foundation series, from Isaac Asimov (and basically, in my taste any book from Asimov has some good chances to be good)
- Hyperion, from Dan Simmons (a good scifi writer as well).
Really, anything by Michael Crichton.
Snow Crash - Neal Stephenson