I could write a book on sci fi books and authors. Here are a few to start.
For sci fi clever comedy, Terry Pratchett has written the tremendously entertaining Disk World series. Dozens of books in the series, each better than the last.
For old fashioned sci fi, Robert Heinlein is my favorite author. Such a great writer. I almost cried when he passed.
Spider Robinson writes edgy sci fi. His Callahan's Crosstime Saloon series is another great comedy, thinking sci fi series. He also has other regular sci fi books that are good or great.
If you want some old space opera, the Lensman series by E.E. "Doc" Smith has the forces of good battling the forces of evil over half a dozen books. Good stuff although it's getting dated.
Roger Zelazny is the best for Sci fi/fantasy. His Amber books chronicle the lives of a family of near gods. Well written.
Not really sci fi but anything by Clive Cussler is worth reading. The older (best) stuff was written by him. Now he's so successful that he has ghost writers write various series in his style.