Every book has a totally unique world with its own politics and religions and science/magic. On top of excellent world-building and delicious pacing and superbly natural explication, Tepper shows deeply complex characters who come from a wide variety of positionalities. And unlike 99% of books with female main characters, the story does not center around romance or men. And people of color are included without stereotyping or relying on tropes. There could and maybe should be more main characters who are queer, but queer people are included in most of zir books, and their queerness is just another aspect of their personality.
Overall, Tepper's work is ethical and brilliantly crafted meaningful storytelling. Also, all of zir books (that I've read so far) are dystopian and spotlight patriarchy, ecocide, capitalism, religious control, and/or fascism. Chillingly true, most of the time.
This is based on:
After Long Silence (read a LONG time ago and just realized it was Tepper!)
The Awakeners (omnibus of NorthShore and SouthShore) has literal zombies, but in a unique way, for a unique reason, and it comments beautifully on religion.
Beauty (the first one I read, horrifying to the point of almost-but-not-quite-too-much, a triumph of balance. it's like grimm crossed with orwell.)
Gibbon's Decline and Fall
The Family Tree (my second of zir works, which made me fall in love. I find the idea of nature taking revenge to be thrilling and happy. It's my favorite.)
Singer from the Sea
The Visitor (what I consider to be zir best work, out of what I've read so far. Comments on christian fundie-ism, bodies, sex, etc, it's creepy and includes elements I think some would find horrific, but I found it cathartically symbolic.)
Raising the Stones (currently reading)