Fastmail is very good. The web client is pretty simple, but feels so darned responsive (as in fast) compared to what I was used to from GMail. And spam is so far a non-issue.
With your own Linux instance, you can host whatever you want, have full control, can host other services too like www, git, whatever, and have the assurance that you're not going to suddenly lose access because AI-BOT-204432 decided you violated some obscure terms of service. I've been doing this for close to a decade now (exim + dovecot for E-mail), and it works great. Back in the 90's, this used to be the default. How did we end up in this world where we so utterly rely on 3rd parties for such everyday critical Internet services?
The same way we ended up in a world where we so utterly rely on 3rd parties for such everyday critical services as growing our food and fixing our cars. There's too many things to do for everyone to do them all on their own.
For email? Because Google and Microsoft broke SMTP federation in the name of "anti-spam".
It's practically impossible to get Google, especially, to reliably deliver your email anymore if you aren't an actual email service provider.