You mentioned Arthur C Clarke, Max, but none of his books....the 2001 series (2001, then 2010: Odyssey Two, 2061: Odyssey Three and 3001: The Final Odyssey) would have to be included in any list of mine. I appreciate that 2001 is also a film - actually the book and the film were made concurrently - but it stands on its own as a good read.
I must admit that I did like "Rendezvous with Rama" and I also liked "Cradle" which he wrote with Gentry Lee ... but if you were introducing someone new to science fiction and you knew that they would only read "so many" books ... would you put these on the "must read" list?
Horses for courses I guess, or "one man's meat..." but ACC has always been a favourite of mine.
Clarke, Asimov and Heinlein were reckoned to be the "Big 3" and I heard that ACC and Isaac Asimov had a mutual agreement that they were "the two best science fiction writers" which is maybe a bit arrogant, but I'd reluctantly go along with it...
I am not certain that I would introduce someone to science fiction with the “Crème de la Crème”. Some good SF might scare off a novice.
To "Dune" and "The Moon Is a Harsh Mistress", I might add "The Mote in God's Eye" (Larry Niven and Jerry Pournelle) and "The Dispossessed" (Ursula K. LeGuin).
One of the strengths of science fiction (and a reason that some prefer the term speculative fiction) is the ability to ask "what if" in a way that can often be less limited by local cultural biases.
I admit that I also liked Gordon R. Dickson; the feel-good stories were fun, the sad stories were touching (sometimes painful), and some had fairly deep ponder-worthy content. I do not think I would class any of them in the best of the best category, though. Likewise, Lois McMaster Bujold's works are very enjoyable, but I doubt I would list any among the ten best SF works (though I would be more willing to recommend such to a novice because they are fun).
Yeah, if we were on the same continent we'd probably be thumping hell out of each other right about now....
Tell you what....if we ever DO end up in the same end of the same continent, we can sit down and thrash it out over a beer or 3 (like Nietzsche in your philosophy blog)?