I’ve been using yahoo forever, is there a reason why u shouldnt be using that?

you could've googled this my man

imagine not using gmail

Theres too many option out there.

Gmail prolly the best cuz it separates everything and tags stuff with social promotion etc and if you have youtube account you have one already

Can't go wrong with Gmail to be honest. If you're big on privacy, Protonmail would good as well.