There are some great novel recommendations here, but I wouldn't say that most of them are lesser-known.

What are your recommendations?

As for me, I've exclusively read well-known novels, except if you consider someone like Alfred Bester obscure, for example.

One exception: Misha Burnett's Endless Summer: Twelve Strange Tales of Mankind's Future. It's a collection of exceptionnaly well-crafted stories. It ain't a novel, though.