Lots of great sf/fantasy authors mentioned already, including some I’d argue for as great writers regardless of genre (Ursula K. Le Guin, Gene Wolfe, N. K. Jemisin).

I have three more to suggest in this genre and from this period:

• C. J. Cherryh (Cyteen, Foreigner series, lots more) uses the lens of alien societies – just different enough from ours – to make us look critically at the structure of our own;

• Sheri S. Tepper (Grass, Raising the Stones, The Gate to Women’s Country) carries one or another of the dark currents underlying our culture to its horrifying conclusion, and shows us what we get;

• Lois McMaster Bujold (Vorkosigan saga) gives us a hilarious and improbable hero who utterly transcends his disabilities, in the end perfectly embodying what it seems he could never hope to be.