Ask HN: What’s your most underrated sci fi favorite book?

I'd choose one of these two, since they both completely qualify as underrated:

A) "Psychohistorical Crisis" by Donald Kingsbury, which is an unauthorized sequel set in the world of Asimov's Foundation Series.

B) "Venus Equilateral" by George O. Smith, which is an old, rather cheesy sci-fi novel from the 1940s, which is basically a bunch of engineers on a communications space station fighting lawyers, bureaucracy, and space pirates through inventing stuff.

I enjoy Adam Roberts, and he doesn't tend to get much mention on HN. I particularly enjoyed Salt and New Model Army.

I also enjoy Allen Steele, and again he doesn't get much mention on HN. I really enjoyed the Coyete series, although many people get stuck on the lack of science in them.

I don't know about underrated, but I also loved reading Interzone when I was younger, and the anthologies are great if you can get hold of them.

I have no mouth and I must scream - Harlan Ellison (Short story) We are Legion We are Bob - Dennis Taylor (Highly rated. Good anyway)

“The Man Who Folded Himself”

Probably the best time travel book I have read!

Don't know how highly rated Iain M Banks books are, but they are brilliant

"The Revolving Boy", by Gertrude Friedberg.