If you would have the power to change any Emacs-default setting, what would that be and why?

What kind of setting do you think would be useful for a lot (or a majority) of Emacs-users?

One of my examples:

(fido-vertical-mode t)

Because seeing a list of candidates as you type and being able to choose from it with meaningful key-bindings is way more convenient and efficient than the tab-completion-system (I think this claim is backed by the way all those external packages work; helm, ivy, vertico). This is especially suited for a default because you can still use the tab-completion-system with it. So nobody needs to change habits.