I haven't read it in a few years, but if you like fantasy (magic, swords, etc) The Name of the Wind by Patrick Rothfuss is fantastic. My only issue is it's supposed to be a trilogy. He finished the second book 10 years ago and the final book has been in final edit for several years.
If you like sci-fi I really liked Red Rising by Pierce Brown. It's another trilogy, but then he wrote two more. I would stop after the third book though. I didn't care for volumes 4 and 5 as much. Part of it was it had been a few years between 1-3 and 4-5. I had forgotten many of the characters so it was harder to pick up the story.