When I’m selecting any new service the first thing I consider is security. Do I trust this company to keep my username, password, name & address, and possibly my credit card data safe? In this case I trust Apple, Fastmail, and Google equally.
Next, does this email service have all the features I need? In my case Apple does not and Google does. I’ve never used Fastmail but from all reports it is an excellent service.
What about privacy? Based on their policy statements, neither Apple, Fastmail , or Google sells information about me to third parties. Apple advertises Apple products on Apple services to Apple users. And Google sells targeted ads that they present to people who use Google services. But they keep what they know about me to themselves. Otherwise advertisers would not need to buy ads from Google.
Do they keep my emails private? Nope, how could they? They only have one copy of my messages. There are multiple other copies of all my messages in servers, personal computers, phones, and tablets, etc. around the world.
So, why do I use Gmail & Google Workspace? Google’s server side rules are excellent as is their spam filter. Their contact list and calendar sync well with Mac & IOS Contacts and Calendar and their IOS mail and calendar apps are reliable and have all the features I need. And their price for Google Workspace is competitive.