C.J. Cherryh
The Pride of Chanur - nominated for 1983 Hugo Award, if you like Orson Scott Card, David Brin, Larry Niven or Lois McMaster Bujold.
Cyteen - won the 1989 Hugo Award, if you like Ray Bradbury, Arthur C. Clark, Vernor Vinge, William Gibson and Philip K. Dick. NASA named an asteroid for her, saying she challenged their view of future of mankind in space. Unfortunately I don't see it in ebook anywhere and she's very close to having recovered the rights to much of her backlist to offer ebooks from her own site, so this may be legally available shortly.
I'm not in love with her fantasy stuff, very much like about half - but most of her sci-fi knocks my socks off.

I can definitely recommend to anyone
The Pride of Chanur, Heavy Time, Cyteen and
Merchanter's Luck as some of the best stuff in sci/fi. I can also whole-heartedly recommend the rest of the Chanur books but only the first 2 of the 3 book followup trilogy (Chanur's Venture, The Kif Strike Back) are ebooked. Missing Chanur's Homecoming from the trilogy.
This is my Cherryh great stuff list. Don't try the other Cherryh stuff until or unless you're hooked and already know how good she can be. Like I said, not much is available in ebook. The Foreigner trilogies for example, the very first book isn't available lol..
Chanur
1. The Pride of Chanur
2. Chanur's Venture (1 of trilogy)
3. The Kif Strike Back (2 of trilogy)
4. Chanur's Homecoming (3 of trilogy)
5. Chanur's Legacy
Heavy Time
Hellburner (read Heavy Time before Hellburner)
Downbelow Station (Foundational novel 1)
Merchanter's Luck
Rimrunners
Tripoint
Finity's End
Cyteen (Foundational novel 2)
Regenesis (Foundational novel 3)
(all standalone but this is roughly chronological order)
Foreigner 1
1. Foreigner (1994)
2. Invader (1995)
3. Inheritor (1996)
Foreigner 2
1. Precursor (1999)
2. Defender (2001)
3. Explorer (2002)
Foreigner 3
1. Destroyer (2005)
2. Pretender (2006)
3. Deliverer (2007)
(read as trilogies)
Faded Sun
1. The Kesrith (1978)
2. The Shon'Jir (1978)
3. The Kutath (1979)
Fantasies of hers that I liked a lot -
Angel with the Sword
The Morgane Trilogy (Gate of Ivrel, Well of Shiuan, Fires of Azeroth)
Rider at the Gate (kinda combo sci/fi - fantasy, gotta love carnivorous
horses who think the greatest thing humans brought with their
colonization team was BACON, heh)
The Paladin
The Goblin Mirror