Ancillary Justice (Anne Leckie) <the sequels aren't very good though>
The Long Earth (Terry Pratchett & Stephen Baxter)
The Martian was a page-turner for sure but I think it actually worked better as a movie.
This is tough, I just realized how many of my favorite books I read in the last 5 years were actually written in either the early 2000s or the 1930s.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.