I self host. Don't.

Proton. Yes.

I used to pay for Gmail, then I used Proton Mail about a year, and I’ve been using Fastmail for the last couple of years, which I recommend. I don’t know of anything that’s as feature-rich and easy to use as Fastmail. You may not be interested in all those fancy features, though.

I use MacOS/iOS Mail clients, but also Thunderbird as I’m trying to wean myself off of Apple’s ecosystem and onto Linux/FOSS.

Protonmail, it's fantastic. Sleek design, solid feature set, integrates with Thunderbird if you want to use that.

Fastmail, 100%. Reasons:

• "Encrypted email" only works between encrypted providers. ProtonMail and Tutanota are both very inconvenient, and all I want is an email that's not scanned for marketing.
• Since 2018, ProtonMail kept getting worse, especially with the recent AI stuff. Dodged bullet, IMO.
• $6/month = Custom domains, and any amount of emails under those domains. I can send and receive from any domain xxx@yyy [dot] lynndotpy [dot] dev, for example.
• CalDav and CardDav provider = Contacts, calendar, and reminders sync. Works perfectly on iOS too, if you like that.

It replaced my finnicky NextCloud for half the cost.

ProtonMail. Works great for the most part.

Except their desktop "app", which is total shit. It's just a webview in an electron framework. If I wanted to keep a webview, I'd just keep a tab open in my browser. Or a separate browser window if I wanted to keep it separate.

Mailbox.org with my own custom domain (firstname@surname.co.uk) and Thunderbird for an email client.

I would highly recommend it. It is cheap and includes almost a complete replacement for Google services (email, contacts, calendar, online drive, etc).

Please consider your privacy. Giving all you emails to Google (or other mainstream data harvesters) basically gives them deep info about your whole life (purchases, travel, communication....everything).

Having a custom domain let's you go to any provider you like if you want to switch.

Posteo. Happy with them. For client, gnus in Emacs. Have it configured to do Autocrypt too, but almost nobody else on the planet does 🙁

Tuta. It's great but no third-party client support.

I self host, on a personal domain I registered in June 2000. Mostly followed a 13?-part tutorial at I think linuxbabe dot com, was the first one that seemed to genuinely be trying to help you set up a good environment, not just as a way to say “doesn’t this sound difficult? Impossible even? Coincidentally you can pay us to do this instead.” Except I put everything on its own VM instead of all on one. (Even a VM for just opendkim, which was maybe not necessary.)

Mostly iPhone mail app and/or Roundcube webmail.

Yes highly recommend it, for receiving email. Greylist blocks like 99.8% of spam. Sending works fine for me, because it’s an old domain with history. I don’t think brand new domains have the same experience.

Proton for personal email. Not immediately needing to escape but once my free email runs out of storage I plan to switch to something else because of the concerns raised by the incident with the French climate activist.

Gmail and protonmail. Both give me no issues at all.

Mxroute with thunderbird as a client and mail on iOS for mobile.

Unlimited domains and rock solid. Just don’t expect lots of hand holding the company focuses on making email work you have to sort out your own details. That being said they have good documentation.

Zoho, because it's email server is free to use for custom domain adresses

Ionos.
Too lazy to selfhost. Also the implications of self hosting and securing email is too cumbersome to sleep well at night.
But I do self host non-important to my living at home.

Edit:
Inbox: Outlook. Tried eM-Client but it was worse than Outlook (around 2018 or 19)

Purely Mail, yes; so long as you're comfortable with one guy running the service.

Thunderbird for desktop and K-9 for Andriod. Only because they were the most recommended and completely fit my needs.

Answer to the bonus question: http://mutt.org/

My own. With blackjack and hookers.

As a client I use Kmail. But I'm not really satisfied. Kmail 3 was so great, I miss it. I should go back to Thunderbird.

Migadu. Yeah*. On the computer, I use mostly aerc (+notmuch), but hop on Thunderbird once in a while; on mobile I use K-9.

* If you are not looking for totally free options (though their cheapest plan is 20€/y and they give 50% discount to students), and if you don't care about email encryption (which you shouldn't). Migadu has a very good Pros/Cons page, I highly recommend you take a look, even if you're not using or planning to use their service.

Gmail.

No.

Tuta, wouldn't really recommend it since I can't use it with Thunderbird or as an SMTP server

Proton, yes, thunderbird

gmx.com

It used to don't require phone number

I recommend it if you're not using for privacy sensitive use cases, has both IMAP and pop3 for free

I use gmail and my own domain with uninbox. The latter is a quite new FOSS email front/backend, but its still very new and lacks essential features.

If I'd make the switch, it would probably be to tutanota.

Gmail, wouldn't recommend. Use it out of necessity.

I use k9 mail for checking on mobile and it is solid most of the time