Frank Herbert and Heinlein would be my top 2. Best Sy-Fi movie would be “Blade Runner”.
I’ve read “The Lazarus Effect” and all the Dune books by him. Not bad but the movie sucked. The HBO series was much better. Blade Runner is sort of the Bach of sci-fi movies. I like Larry Niven books for the realism, and I wish they would make movies like that.