I use mostly POSIX shell for scripting: using either /bin/dash or busybox's ash.
I use awk each time I need to work with formats which have 2 characteristics: 1) context-dependent informations (like `ip link`'s output, or subsets of YAML, like /var/lib/dpkg/status (ok, it's older than yaml, but a lot nicer, too)) and 2) do not embed strings which support escape characters (like «"hello \"world\"\n"»). Luckily, many shell utilities have such outputs.

When those do not suffice, I usually go with my simplified C++ setup (no exceptions, no RAII, can be statically linked), because I'm too lazy to learn perl.
Python is a no-go for unpaid work: I think a turing-complete language that uses whitespaces as syntax element is a bad idea. Also, I tend to favor things which do not break backward compat and/or have an actual standard, not just a "reference implementation", because I hate restarting from scratch every few years.

Recently, I started playing more seriously with prolog, and I think it might also become a powerful scripting tool, for when I write code which must take different paths depending on pre-conditions. This is a language which feels really powerful to write IAs, sure, but it also feels interesting to check for dependencies, and it came to my mind it might be interesting to use it for things like my runit control files or, why not, generating ninja files to build my C++. Maybe even not bother with ninja files and directly summon compiler, since prolog may be even more suited than ninja or make to do that job.