I think Gauche is better than Guile. Its manual is easier to navigate, its standard library is huge, and it's fast enough for anything I'd ever need it to do. Both tools are fine, but personally I'd choose Gauche of Guile every time.
It is definitely nicer to do shell scripts in, but I have other things written specifically for guile using delimited continuations and guile-fibers. Since concurrentML is the only way of writing concurrency that I like I am pretty much stuck with guile since it has what is probably the best implementation.
Guile is noticeably faster as well, but that is not really surprising considering the implementation differences.
also several python3 packages and many others that were installed as dependencies from the above that i didn't check if they too depended on something that depends on guile.
strictly speaking it is just make and gdb that depend on guile, but gcc depends on make and many other packages depend on gcc.
it appears that on debian make does not depend on guile.
but since i mainly use fedora, all my machines are likely to have guile installed.
I believe Guile scripting is an optional (compile-time) GNU Make extension, so whether or not it's a dependency will depend on how GNU Make is packaged. The others I have no idea about, but I do wonder if these are mostly transitive dependencies via Make.