I think landofnowhere (my coworker in a mathy capacity, possibly a mutual acquaintance via Boston people?) liked Middlegame. I went to a non-mathematical McGuire reading at WorldCon a few years ago that cemented my impression that she's good at doing a thing that isn't my thing.

I would have guessed Memory for Nebula and Gideon for Hugo, but maybe my sense of which prize is artier is out of date?