Debian Slim all the way. musl is only good when you are building for and testing against musl. Third party software on musl has burnt me enough times to know that sticking to glibc is the way to go unless you like that sort of pain.

Footnote: I actually love musl, just for my own software that explicitly targets it and is validated against it.

I would strongly avoid Alpine.

Most software isn't written with Musl in mind! And that shows.

You can run in all kinds of extremely hard to debug issues and especially massive performance problems. Stuff may slow down to fractions of the performance comparison to regular Linux distros.

If you want maximal small containers go with Distroless.