It's strange to start a list of "books that you may never have heard of" with a novel which is a nominee to the 2020 Hugo Awards. I suppose that most of the regular readers of sci-fi haver heard of it.
A nitpick about the third recommandation with "robots modeled on Karel Čapek’s designs". I suppose that they have not read Čapek’s novels. His robots were not pure machines, they were made from a biological substrate. In a way, they were closer to golems than to what we're now calling robots.
If you want to read really different and lesser known novels, Karel Čapek’s are a good choice. I did not enjoy "R.O.R." much except for his surprising concept of robots, but I highly recommend "War with the newts".