One important thing missing from BusyBox:glibc is the SSL certificates that's almost always needed if you are writing things like crawler etc.
As for Alpine, at least for packaging Python code, avoid as much as possible. It cannot reuse manylinux packages on PyPI and have to recompile C modules.
With Alpine, the size advantages of musl sometimes come with hidden overheads as well.
Musl's malloc() seems to be a fair bit slower than glibc's when you start to throw in more threads at it (fragments faster?).
And then if you try to replace that with jemalloc, you'll quickly find out that jemalloc does not actually get used.
At some level, the difference between a 1Mb docker image and a 9Mb one isn't that significant (& I asked for some things like strace, ping and nslookup to be in it, because it gets impossible to debug the container when it obviously caches a DNS record or at least, looks like it is doing that).
As for Alpine, at least for packaging Python code, avoid as much as possible. It cannot reuse manylinux packages on PyPI and have to recompile C modules.