I script everything in bash, but for everyday use fish just has some modern QoL things that make it easier to get around. For me, specifically, it's the way you can recall commands by seeing a ghost version of your history, as you type. You can even scroll through a filtered history if you're part-way through typing some long command that matches what you have typed.
Another neat thing, it does it's best to predict what I want to type and remembers common locations, showing them as ghost text as well.
zsh is just a fancy shell with its own scripting language, and like anything in Linux-land all variations on a theme must be at war with each other! Kinda like Vim vs eMacs.
Abba's car keys?