Get a domain from Gandi. $15/year and includes email service. You can either use the email directly, or forward it somewhere else so you can keep using the same email address forever even if you change providers.
Wow, didn't know that. Seems like a pretty good deal considering they are known as one of the better registrars. I will keep it in mind in case I have to look for alternative of either name.com or mailbox.org.
Mailbox.org as of now seems to be good except that they have started to either reply to emails quite late or sometimes simply ignore it[0] and the general lack of non-German language pages across their portal [1].
[0] Maybe because they have officially stopped anything but community/forum support for paying customers in €1 and €2.5 per month plans -https://mailbox.org/en/fees-and-conditions/
I have no idea how you can compare Gmail to Thunderbird + your own domain + any decently sized email provider. It's absolutely trivial to move domains and email providers and using a client like Thunderbird means your experience remains consistent (and performant) over time.