Isaac Asimov is one of the classics, of course. I'm particularly fond of the robot novels (all four of the Elijah Baley ones especially) and the entire Foundation series. Of course, you also can't miss the robot short stories. Oh, and The End of Eternity! At some point I found Charles Stross' Accelerando, which is freely available online (along with a bunch of other short stories), and found everything I've read (which is most of it at this point, I think) enjoyably fast-paced. In particular the Laundry series (of which I've bought every iteration as soon as they came out over the past few years) -- though arguably these maybe cross-over from SF into fantasy a bit -- and the Halting State trilogy.…
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