For me, the most recent book regret is Dark Matter by Blake Crouch. Predictable from the get-go, bland, boilerplate sci-fi ideas, too many of these way-too-convenient plot devices just to push the story forward. I frankly don’t get the hype, and I am a pretty big science fiction guy.
Another one is Blink by Malcolm Gladwell. I read this in college and this whole book should have been a one-page essay. It was too repetitive, and the whole premise of “trust in your snap judgments and gut reactions” is way too simplistic and honestly stupid. Like all Gladwell books, it was anecdotal, superficial, and a waste of time.
Hub by Matt Shaw and Playground by Aron Beauregard. I wanted horror that would actually affect me, but the only thing that affected me was how bad the writing was. I regret them but at least they taught me extreme horror is extremely bad.