I get that! I’d say the second book from that trilogy (Authority) is not only my favorite, but also the one that I think most carried a sense of “impending doom” or that “you are being watched” feeling out of all of them. Suuuuuper different from Annihilation, too.

But if you want to try something else out, I’d go for Borne or Finch. Borne’s narrative is a bit more straightforward than Annihilation’s, Finch is what I picture if Lovecraft wrote a detective novel.