We've used Eleventy on a project a year ago and it was super easy to get running. It is not tied to any frontend framework (but if you want an interactive part on the page, you will have to set it up yourself, in contrast to Astro's Islands [1]).

My overall impression is: use 11ty for a first version, use Astro when you have more moving parts on the frontend.

Little bonus for those coming from Python background (like me): 11ty uses Nunjucks, which is a JavaScript port of Jinja, so the templating system feels right at home.

[1]: https://docs.astro.build/en/concepts/islands/