The Fifth Season: The Broken Earth Trilogy #1 by N.K. Jemisin
I am not sure that any trilogy has achieved each volume winning the "Best Novel". Of course, I am not sure that any novel has been able to maintain such consistency and depth of characters, while revealing a complex future world with both fantasy and science fiction elements and such intricate plotting since Dune. I am now addicted to this series and to these people's struggles, discoveries and triumphs that become defeats.
The Broken Earth is a potential future in which not climate but geothermal calamities transform both the earth and humanity to such a degree as they are almost unrecognizable. This disaster cast aside the ancient prejudices between men and women and races, but new, even more deadly prejudices emerge. With each marginalized group comes their own power and their own powerful guards, both human and systemic. Behind the surface we see how ability, fear and bias work together to be innately human, but also foreign to humanity.
I'm devouring the second book at this time, now.