I think 'Dune' is one of the most popular. Its epic scale, with deserts, sandworms, and complex characters, has attracted a large number of fans. Then there's 'Starship Troopers' which is well - liked for its military - science - fiction aspects and its exploration of citizenship and duty.
I'm not sure which ones are the most popular exactly, but 'Snow Crash' by Neal Stephenson is often highly regarded. It's set in a future where the world has been transformed by a new form of technology and virtual reality, and it has a really unique and engaging plot.
Another popular one might be 'The Uplift War' by David Brin. It's part of a series and in 1989 it was attracting a lot of attention for its unique take on the evolution of intelligent species and the politics between them.
I'm not entirely sure which ones were the most popular, but 'Doomsday Book' was widely talked about. It had an interesting premise of time - traveling historians.
Another popular one could be 'The Uplift War'. It was part of a well - known series and had a lot of fans who were into the idea of the uplift concept, where lower species are 'uplifted' to sentience by higher ones. It had exciting battles and interesting alien species interactions.
'Gateway' is also very popular. Its exploration of human nature in the face of the unknown, along with the unique setting of the alien space station, has attracted a large number of readers. People are drawn to the mystery of the ships and the potential for discovery, as well as the well - developed characters.
'Wool' by Hugh Howey was quite popular too. It's set in a post - apocalyptic silo, and the mystery and the characters' struggles within that confined space were really engaging for readers. The story gradually unfolds, revealing more about the world outside the silo as it progresses, which kept readers hooked.
Well, 'Dune' by Frank Herbert is likely in there. It has an incredibly detailed and complex universe, with political intrigue, unique ecosystems, and a hero's journey. Also, 'Foundation' by Isaac Asimov could be part of it. Asimov's work in this series is about predicting the future of civilization through psychohistory.
Among the essential science fiction books, 'Ender's Game' by Orson Scott Card is really good. It tells the story of a young boy, Ender, who is trained in a military academy in space to fight an alien race. The book is not just about space battles but also about ethics, leadership, and what it means to be human. Another one is 'The Hitchhiker's Guide to the Galaxy' by Douglas Adams. It's a hilarious and absurd take on space exploration, filled with unique alien species and strange planets.
'Contact' by Carl Sagan was also very popular. It was a thought - provoking story about the search for extraterrestrial intelligence. The movie adaptation also helped to boost its popularity. It delved into scientific concepts as well as human emotions when faced with the possibility of first contact.
One of the most popular was 'Hyperion'. It has a very unique narrative structure, which attracted a lot of readers. The world - building is also extremely detailed.