I joined audible, I have burned through 450 books in the last 3 years...
1) all books that have been made into films are really good, much better than the films, contact, enders game, battle field earth (really long but good much better than the film) hunger games series, the martian
2) anything by the authors listed above
time riders series, ring world series and all associated books, Stephen king the stand, and the dark tower series... there are one or 2 duds in that series but overall good
Frederik Pohi heeche (or how ever you spell it) series there are a load in it,
there is a list of the top 250 scifi books (just google top scifi books) just about all of the books on the list I enjoyed
B V Larson swarm force series is good, loads of books in it... Undying mercenaries series as well
Douglas Adams hitchhiker's series of books are good, I always chuckle when I think about the space ship trying to work out whats going on and how it deduces its god a hole in it...
John christophers tripod series
Ilium/Olympos by dan simmons really good
john varley titan (that's one of the books in a series of several)
Clifford D. Simak way station is unexpected and good
oooww inverted world is really interesting and different
roadside picknic is slightly different and I enjoyed it
Jack Campbell the lost fleet and other space bok,s I think he is x navy so puts a different spin on things
Ex-Communication - there is a series of ex-heros books more superhero but I like scifi and I liked those..
Stephen W Bennett Koban series is good, the last book is a bit crappy though
greg bear Eon
PM me and ill try and export my catalogue of books, I return anything crap so its mostly good stuff or stuff I thought was worth the £4