GNU Bash + GNU Emacs (an interactive shell to a running elisp interpreter)
Since I contribute to NixOS, our builder expressions are in Bash so it helps to be familiar with it. Elisp is always fun to hack on.
I don't really get the shell hype. Especially with Fish since it can't be used as a POSIX compliant login shell. Zsh to me has always been the "apple shell"
Still waiting for the GNU bash release that finally complies with XDG and I can throw that .bashrc out of $HOME