An interesting list is the The Internet Top 100 SF/Fantasy List. I think it's a little biased, but there are certainly some good books on the list.
Other authors/links that I find interesting include:
Lois McMaster Bujold's Adventures of Miles Vorkosigan are compelling reading. Miles is a fascinating character who must struggle against physical frailties, bigotry within his father's chauvinistic culture (Barrayar), and (interestingly) a goodly degree of bigotry of the reversed "overly-politically-correct" variety from his mother's more "enlightened" culture (Beta).
Some T-shirts are available...
Like most publishers, they sell quite a lot of worthless books. But they have some very good authors. Baen carries more than the average percentage of books of "military" science fiction; their authors tend to be on "the right wing of the bird."
In the "Greg Mandel" series (Mindstar Rising, A Quantum Murder, The Nano Flower) he presents a not-quite-utopic, not-quite-dystopic future. New technologies, but classic human motivations. He rightly sees that technology can and will be used both wisely and unwisely, for good and for ill. And he's very good at producing unexpected plot twists. The end is not what you expect it to be at the beginning...
In the realm of "Hard" Science fiction, where the goal is to present the use and abuse of future technologies in a "realistic" fashion, Larry Niven has long been one of the top authors. His "Known Space" books have been presenting "What if?" stories for many years.
And then there's Man of Steel, Woman of Kleenex, an essay that describes seriously and technically why a physical relationship between Kal El, aka Clark Kent, and Lois Lane is completely implausible. They most should furthermore not try to have kids. Niven may present the information calmly and quite rationally; the overall result is nonetheless a scream.
Rainbow Mars by Larry Niven
Vernor Vinge is a notable author of "hard" science fiction whose works I find spectacularly good.
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