My favourite SF book this year was "Translation State" by Ann Leckie. It is set in the Imperial Radch world so having read the Ancillary trilogy is useful but not essential.
I like it because it contains the strangest aliens (the Presger) that I have come across. They are as far from humans in costumes as you could get. What the Presger do (and their proxies in the Human world the Translators) is totally unguessable.
A fabulous hard SF read and a must if you read the Ancillary trilogy.
I can warmly recommend anything written by Leckie. Her scifi is great. But her attempt at fantasy (The Raven Tower) is also most excellent.
I enjoyed it too, but I was already a big fan of the Imperial Radch series. Does it work standalone also?
Edit: just to add that the audiobook is really well narrated
I enjoyed Translation State so much. It thought that Leckie got lost in the depths of Octavia Butler’s extra weird shit (and Xenogensis) and cross bred it with the political novel style of the Ancillary trilogy, and the result was chefs kiss.
I feel comfortable recommending it even if you haven’t read any other Leckie.
Edit: if you haven’t read the Bloodchild anthology by Butler, give it a read. Some of the short stories will seem very familiar after Translation State, especially the alien parts.