Ask HN: What were the best science fiction books that you read in 2019?

I read all of The Expanse. Fun series that takes place after we've colonized the solar system with infighting between Earth, Mars, and those who live out past the belt, when suddenly an alien artifact shows up.

Influx (a large secret govt. sect suppressing technology breakthroughs and keeping it for themselves) and Kill Decision (autonomous killing drones) by Daniel Suarez were fun. I liked Deamon (a murder mystery of sorts where the murderer is already dead and automated scripts and whatnot carry out the deeds) and Freedom (part 2) better however.

Beyond what I've read this year in Sci-Fi, I would recommend the Hyperion saga (my vote for best sci-fi ever), The Martian, Ready Player One, Snapshot (a short by Brandon Sanderson, my favorite author by a wide margin), and, heck, while we are at it, the whole of the Enderverse, though I preferred Speaker for the Dead, Xenocide, and Children of the Mind the most).

It has been said that the difference between sci-fi and fantasy is spaceships vs trees. If you are looking for fun fantasy, I suggest just about anything from Brandon Sanderson. He has his Cosmere universe composed of many book series, the best of which are the Stormlight Archives.

"The Black God's Drums" by P. Djeli Clark was a great novella.

https://www.amazon.com/Black-Gods-Drums-Dj%C3%A8l%C3%AD-Clar...

I enjoyed 'We are legion'. https://www.amazon.co.uk/Are-Legion-Bob-Bobiverse-Book-ebook...

A Memory Called Empire was interesting as concept, maybe not a top plot.

Started Ada Palmer’s series as audiobooks, did eventually get hooked. Rich in plot.

I re-read Salt by Adam Roberts and I enjoyed it a lot. The conflict feels real and understandable, and I liked the ideas.