I’ll be honest, I use bash and the only benefit using ble.sh has over zsh, is that vi(m) mode is better than zsh. For example, more complex commands like di" (delete inside ") don’t work in zsh, but work in bash with ble.sh. Also, I found ble.sh far more complicated and took me a while to get it configured. Even now, some completions, especially tab completion, isn’t as good in bash as in zsh. In fact, the only issues I had with zsh compared to ble.sh were vi mode related. More specifically, the aforementioned lack of advanced vi(m) mode commands, and the limited support for showing the current vi mode in the prompt, for example for Visual mode (Normal and Insert mode seem to be the only ones to work).

So if you need advanced vi(m) mode, get ble.sh configured. Otherwise, go for zsh.