That was precisely my first question, so thanks for the answer, but I don't really see how that's enough to switch… I've been using this "cleaned up/opinionated" fork 'Prezto' for a while now: https://github.com/sorin-ionescu/prezto
If I'm motivated enough to download and install a shell, why wouldn't I just clone Prezto and change one config file to turn on syntax highlighting and git support? Especially when it doesn't bring any "weirdness in command substitution" and I get the great zsh expansions and completions?
Anyways, I'll try it out (why not?) but the benefit to me wasn't clear from the page, and even with your direct clarification here I'm seeing more downsides than zsh + Prezto and not a significant upside.
It's been many years since I've use zsh, so I won't pretend to know what's state of the art with it. I will say that one of the reasons I use fish is it's incredibly easy to customize. My old bash config just came along with me from years of use. Some of it I understood, some of it was just culled from the Internet and kept working, so I kept around (see: prompt customization). But, other than simple aliases, env var setting, and the occasional function, I didn't bother much with shell customization. I find fish simple enough that I can write a new function or tab completion and not have to spend a day figuring out the bash syntax again.
Writing tab completions in fish is really, really simple. It's the thing that initially sold me and it's kept me hooked.
The history is more powerful than bash, too. Although I find it sometimes works against me. E.g., since it tries to guess your command, things you type in lowercase suddenly turn to uppercase until you manage to disambiguate from a previous command.
If you're looking for plugins, there's oh-my-fish [1]. Years back, the term "fish-nuggets" was popular and you'll find repos named that on GitHub with other configuration. I use a couple plugins, but for the most part I don't need them. I think part of that is because fish is featureful out of the box and part of it is because customizing is so easy. I'll usually just add what I need myself rather than trying to find a general purpose plugin.
Anyway, not a direct answer to your question -- apologies for that. Hopefully something in there is of use for you, however.
If I'm motivated enough to download and install a shell, why wouldn't I just clone Prezto and change one config file to turn on syntax highlighting and git support? Especially when it doesn't bring any "weirdness in command substitution" and I get the great zsh expansions and completions?
Anyways, I'll try it out (why not?) but the benefit to me wasn't clear from the page, and even with your direct clarification here I'm seeing more downsides than zsh + Prezto and not a significant upside.