The best book I read last year was Aurora by Kim Stanley Robinson.
Kim Stanley Robinson writes hard-sci-fi. In the tradition of Arthur C Clark, he wants to explore the question, "If we <went to another planet>, what would it
actually be like?" His books contain no science-fantasy: there is no faster than light travel. There are no anthropomorphic aliens. The universe is what it is.
Aurora follows the journey of a generation ship on its way to Tau Ceti, a journey that will span multiple centuries. The book is told from the POV of the ship's AI. This is a clever device, as it allows the narrative to comment on a lot of stuff happening on the ship while still focusing on a few characters. In the beginning of the book, the AI doesn't really know how to tell a narrative story, so the writing is a little clumsy. At some point, its told to research literature and educate itself - and after that point, it starts using metaphors and more poetic language. The writing style shifts subtly as the book goes on - this is a tiny detail but it helps the whole thing come to life.
The book doesn't really have an antagonist - it's part of the Man Vs Nature sci-fi tradition where a lot of the book is spent troubleshooting the various unanticipated and INTERESTING problems that come up on a multiple-century space flight. Like for example, you've basically created an island ecosystem. And in the real world, that accelerates evolution. Humans aren't reproducing fast enough to experience this, but the microorganisms we coexist with - stomach bacteria, etc - reproduce on a much faster schedule. After centuries, they start to fall out of symbiosis. What the hell do you do about that?
The ship is really imaginative. On a journey this long, they need a ship which creates its own oxygen, food, etc. So they try to create, essentially, a mini-earth. The ship has a bunch of giant spinning cylinders, each one is analogous to an earth biome. So there's a desert biome, a taiga biome, an evergreen forest biome, etc... Within these biomes there are 2-3 villages where people live off the land. There is also an assumption that "wilderness" plays an important role in the ecosystem, even though we still don't really understand it, so there are parts of this world which are off limits. This means that every so often, somebody gets killed by a pack of wild wolves. On a space ship.
I don't want to spoil too much - but it was definitely the most imaginative and engrossing book I read in 2016. Highly recommended.
Here's a video of Robinson talking about the book:
https://www.youtube.com/watch?v=3T1-lE5i98M (with mild spoilers, about the same level as this post)