It's only tangential but switching to fish shell made me about 3 times more productive. Being able to easily recall commands, to have completions displayed as I type, and to have interactivity be a first class citizen of the environment... made working in the shell so so so so much nicer.

Fish has its own quirks, some of which seem unnecessary, but it was a godsend. There is definitely still room for improvement of the old tools, a. lot. of. room.

https://github.com/zsh-users/zsh-autosuggestions

Now zsh feels just like fish, but with bash-compatible syntax (which was the main day-to-day problem I had with fish, otherwise it's fine, but except for the auto-suggestions I didn't really use any special fish features).