I would say that in the era of agentic coding you don't need any framework. Just a backend + router + markdown generator. I use Hono + Tanstack router for the first two. Tell any decent LLM to wire those up for you and you'll have a simple static site ready to go in an hour or two.
Astro is also great (as others have noted) esp if you want to leverage the JS ecosystem at large.
It is more like a dialect of JavaScript optimised for developing static sites than a static site generator in and of itself. It has lots of 'builtins' for things like RSS and converting Markdown to HTML. It is so wonderfully flexible and doesn't lock you into a specific site structure like others SSGs do.
Whatever you use, I feel it is tradition to have 3 odd blog posts about journey of building a SSG of your own since nothing else matched exactly what you needed and that’s it. Then you should forget that blog ever existed.
edit: i mean have the ai write the generator, don't use it to actually generate pages...