Self-hosted. My webhost comes with an email service for upto 200 email addresses. The main advantage is that I get to choose everything. I use that with Rainloop as the web front end and Outlook for native client.
Postfix is pretty reliable, but often blocked on some cloud providers - example, on Google Cloud, you can run Postfix, but you need to tell Postfix to reroute the mail via a third-party provider such as SendGrid. Thanks for the feedback!