It is a little strange as a long time Science Fiction (note SF not SciFi) reader the there are only two authors I would put in the category. Neither of them are SF writers. These are
C. S. Forrester &
Robert van Gulik
Neither is going to win the Nobel Prize for Literature but I have reread them more times than I can remember over the last sixty years and look forward to reading them again. There is something about these books that just grab me.