Oil or Fish Shell?

Fish is pretty decent and so is oil, but I still use zsh because of its POSIX compatibilty - which, in my opinion is a huge plus.

Pimping zsh with powerlevel10k[1], some custom dotfiles and scripts feels like having enough convenience, while still using POSIX. I use "Pure" theme by the way, because it also works nicely in not so modern Terminals, if you replace PROMPT_CHAR with > instead of using the default unicode one...

If there were only these two to choose from, I can't tell you, which one to use. I would just recommend NOT linking the chosen one to /bin/sh, but using either fish or oil for your daily use cases and linking dash to /bin/sh for keeping your OS scripts POSIX compatible and working.

I, personally, have come to the conclusion, that zsh is good enough for me and will be until something revolutionary happens.

[1] https://github.com/romkatv/powerlevel10k

I just use bash. Does what it needs to. No reason to change to something else.