I am a huge fan of Science fiction. My absolute favorite series is "Dune." Frank Herbert was an amazing writer and I even enjoy the additions to the series his son and Kevin J. Anderson have made.
So my question is, what is your favorite science fiction writer and/or series?
Favorite writer? No contest: Robert Anson Heinlein. I have always loved his "voice" and way of looking at things. Further, Stranger in a Strange Land and Job: A Comedy of Justice are naturals for a group of S/F-loving atheists!
As to series, I can't say as I have an absolute favorite. Certainly I've enjoyed the Robot and Foundation series of Isaac Asimov, and of course the "Lazarus Long" novels of my man, Mr. Heinlein. Dune, Dune Messiah, and Children of Dune were good, but God, Emperor, Heretic and Chapterhouse were wasted paper to me. I haven't read any of the prequels, though I might be interested in the doings of the Butlerian Jihad.
Favorite writer? This is going to sound somewhat of a copout, but it depends. Andre Norton in my youth, Anne McCaffrey in my teens, Tolkien, but these were more science fiction/fantasy as it were. Asimov, Heinlein, Sturgeon, and later Orson Scott Card, Harlan Ellison. But for S/F straight, Paul F. Linebarger, aka Cordwainer Smith with his Instrumentality of Man series.