Here's the link to their "Astro vs. X" page. https://docs.astro.build/en/comparing-astro-vs-other-tools/
They compare Astro to Docusaurus, Elder.js, Eleventy, Gatsby, Hugo, Jekyll, SvelteKit, Next.js, Nuxt, Remix, VuePress, and Zola.
(For some reason, this page doesn't appear linked anywhere from their documentation's table of contents, and isn't even linked from the "Why Astro?" page. It's almost like they're trying to hide it or something!)