I use a custom domain for my email because it can be moved to a different service (or my own if I choose) easily.

I won't use Gmail and services like it for multiple reasons, but even if you do, consider a custom domain. You can't just take your @gmail address with you and switching emails is painful in my experience (I used to be an @gmail guy).

You're still at the mercy of DNS (for now 😒), but you always were anyway.