+1 for fish, the autocompletion alone makes it my daily driver. You can get the same in any reputable shell, but I like that it is designed into it from the ground up (the zsh autocompletion plugin brands itself as "fish-like").
It's also compatible-enough with POSIX for most purposes, and supported as an alternative for lots of software (venv comes to mind).
Ooh switching to Fish from Bash could be a nice weekend task. Any tips on common tripping points?
You might want bass (https://github.com/edc/bass) or replay.fish (https://github.com/jorgebucaran/replay.fish) if you need to run bash scripts that modify the shell. I personally use replay.fish (although I guess I haven't updated in a while since my version is still called "bax").