Some favourites of mine in no particular order:
The Peace War and Marooned in Realtime by Vernor Vinge (available together as “Across Realtime”) and anything else by him tbh. They are about a technology that can freeze an area of space in time and the uses it is put to. In the first book it is used mostly as a weapon. In the second, the only remnants of humanity are a handful of people who were frozen in time and wake up to find the rest of humanity gone. They are from societies with different levels of technology, but the book is kind of a murder mystery as well.
The Expanse series by James S. A. Corey. I really like the portrayal of the colonisation of the solar system in this series, and how it splits humanity into different groups. When a technology from an extinct alien civilisation opens a portal to thousands of other solar systems it kicks off a series of conflicts, and the crew of an independent warship, made up of members of the different factions, are central to restoring peace.
Station Eleven by Emily St. John Mandel. It’s about a post-apocalyptic world but with an emphasis on how people try to preserve culture, particularly a group of actors and musicians who travel around performing Shakespeare and classical music. It’s a really interesting take. It’s barely science-fiction I guess but I really liked it.
The Dispossessed by Ursula K. Le Guin. It’s about a physicist from an anarchist moon who visits the planet of his origins, where capitalist and authoritarian communist sociopolitical systems dominate, in order to complete and share the theories he has been working on. It’s a really interesting depiction of an anarchist society, and its benefits and flaws.
The Murderbot series by Martha Wells. Really fun series about a security cyborg who breaks its programming so that it can do whatever it wants. It mostly just wants to watch TV undisturbed, but ends up being dragged into various murdery adventures. Probably one of the most relatable and charming protagonists I’ve ever encountered.
Roadside Picnic by Boris & Arkady Strugatsky. This one’s about an alien visitation that has left contaminated “zones” at several sites around the world where alien technologies are left scattered around. People called “stalkers” make a living retrieving technology from the zones but they and their loved ones end up mutilated as a result.
Stories of Your Life and Others by Ted Chiang - it’s a short story collection but they are really good. The movie “Arrival” was based on one of them.
I really need to read more of her stuff, because I’ve only read that and Left Hand of Darkness, and tbh she’s one of my favourite authors on the strength of those two alone.