Bash, just because everything else already uses it. That and bashisms have infected nearly all of my scripts as I clumsily bump into the limitations of POSIX string manipulation.
I have found some very fun things with sed branching patterns as a result of these limitations though…
https://www.gnu.org/software/sed/manual/html_node/Branching-and-flow-control.html
It’s dead now, but Apricity was the first distro I really enjoyed the look of. Now I know better than to care about out of box appearance.