For me, the main thing fish provides over zsh is nice defaults. oh-my-zsh can be incredibly slow, and without it zsh does take a reasonable amount of scripting

For me, the main thing fish provides over zsh is nice defaults. oh-my-zsh can be incredibly slow, and without it zsh does take a reasonable amount of scripting & setup to make it as "nice" to use (which is why oh-my-zsh exists). I think their "sane" scripting is more about ux for writing short disposable logic (the type you write in a terminal), rather than more detailed/advanced/structured programming that you might save to a shell script file. Bash/zsh walk the line of being usable enoughh for typing terse quick commands (terminal syntax) while also being complex enough for writing large scripts (programming language). They end up being imperfect at both.