I used fish for a couple years but switched back to zsh. I found the incompatibilities with bash/zsh to be annoying at times and finally just decided to do the "When in Rome do as the Romans" do thing and adopt zsh.
I had the same experience (but only used fish for a few months). I am quite happy with zsh after settling on zim [1] for plugins and starship for the prompt (starship supports many different shells) [2]. My main takeaway from fish is was that we deserve great autocompletion. The zim autocompletion module is almost as good as fish.
Sadly, this plugin is a pale copy of fish's power - it isn't folder-aware (fish will offer different suggestions for different folders) and it isn't context aware (fish will try to autocomplete the current line based on the context of the current folder, zsh-autosuggestion will just blindly offer history line that starts with what's typed)
I just use tab complete if I want a file from my working directory, which I actually prefer.
If anybody else is using zsh-autosuggestions, it's really worth looking into configuring it rather than using it out of the box. It exposes some pretty cool options. It was sub-par out of box in comparison to fish, but after some tweaking I like it better. You can do things like ignore history based completions on certain commands (like git, I don't need my last commit message popping up)
zsh-autosuggestion definitely has per-folder suggestions, in normal day-to-day work I haven't seen a difference to fish so far (fish may have added features in the last two years that I'm not aware of, but the basic context-senstive suggestions are definitely supported).
[1] https://github.com/zimfw/zimfw
[2] https://starship.rs