Tbh as I remember it, I didn't find Service Model dark at all. It's just that the satire was not as funny or biting as I could have wanted it to, and it seemed like a novella plot/story expanded into novel length. Alien Clay sounds darker. But then, I've not quite vibed with most robot stories of recent years (I'm hit and miss even on what's arguably the best of them, Murderbot - enjoyed some parts but not a huge fan), and Service Model I enjoyed as a literary exercise in pastiche / intertextuality, but didn't really feel much about.

I've read a few books of his and I loved Children of Time and enjoyed the sequels in particular. Sentient spider civilization? Yes, please.

I didn't realize so mnay of the nominees were sequels. Interesting but also makes it less likely for me to check them out (I read little YA/MG anyway these days.)