I've joined Storygraph, LibraryThing, and I think a few others. Never heard of Bookwyrm before.

I still use Goodreads almost exclusively.

Goodreads is still the competition. If you mean competition specifically between alternative to Goodreads, I think LibraryThing is the most popular by a fair bit. After a quick look around Bookwyrm, it definitely doesn't look like the one I'd choose. I'm mostly seeing "some rando's list of books they read in 2025" and "some rando commented on some random book".

Maybe once it finishes importing my Goodreads list it'll be more useful, but it's taking a while (kaguya was very quick), and my initial impression is that I'm not impressed.

Bookwyrm is built on ActivityPub, you won't have any single server, but a constellation of them

However, its strongest point on it's favor is that anyone creating content on AP automatically has a potential reach of a few million users.