https://qntm.org/ra is also great, especially if you've read Sam's work and want more. It will appeal to technical types: magic is real and has a rigorous mathematical theory behind it, which is cool as far as it goes, but he takes it in an interesting direction from there.
Fine Structure's ending is very optimistic, in fact. (edit: a lot of his short stories are, too.) But yeah, Ra is rather bleak. I guess it's not for everyone, but if you came in from "There Is No Antimemetics Division" it won't bother you.
Then I'm confused about why you followed qntm from Antimemetics, which is already pretty bleak, but not enough to prevent you from reading Ra, which was somehow enough to put you off of his work forever. Why did you stop exactly there, reading more from an author who did something you don't like but not reading any farther to learn that he is capable of more?
I enjoyed it more than the 3 body problem: the characters are better written, their motivations make more sense despite having much less time for actually developing them.
I was really having fun trying to figure out how to make the best of an impossible to solve situation. And the SCP lore is wonderful.
I haven't read _Their Is No [...]_, but I have read _Fine Structure_, another book by QNTM. It's an exhilarating read with some forgivable issues and I'd heartily recommend it to anyone interested in heady sci-fi.
I would never recommend 3 Body Problem. I found it and its sequel to be irredeemably unpleasant.
Perhaps not all that offtopic - Hatetris is what happens when you subvert normal the rules and make the game play against you. Anti-mimetics stories are what happens when you subvert the rules of ideas and make them play against you.
I can imagine a common space of inspiration there.
1- https://qntm.org/scp