Which are the most popular fantasy and science fiction books?

Hi,<br><br>this is actually a question I originally wanted to ask in /c/fantasy and /c/asksciencefiction but then I thought it's more appropriate for /c/creative_writing because I want to know what books are the most popular.<br><br>The reason behind this is that I want to know what the most popular fantasy and science fiction books are. As a writer that means to get to know what the types are that are currently are in fashion. Furthermore, it is interesting to know how the most popular books were written such as the wording used, the level of detail, etc. I heard that George RR Martin and Patrick Rothfuss write on a level as if it would be a real history book, while Brandon Sanderson writes with a more conversational style. I have to admit that I'm not that much into science fiction but I think science-fiction is quite popular in books, something that I plan to read more about. Furthermore, I think most of my readers will expect science fiction instead of fantasy anyway.<br><br>If you know any books that are science fiction but have a quite fantastical setting (like Dune for example), I would be interested in that as well. <br><br>So, do you have any suggestions?<br><br>I already read Dune and I own a book by Guy Gavriel Kay. But what are other books that are recommended? If you know how the author writes (detailed or more conversational) I would be happy to know that as well!