Been using fastmail since 2013 and before that hosting my own for about 15 years. I feel fastmail does a lot of things right, for example one near and dear to my heart is proper alias handling in the webmail interface. I think my only complaint is that they rolled out IMAP compatible 'notes/memo' for emails, but you can't use it unless you use the grouped conversation thingy which I don't like.

Also I get the vibe that the company treats their employees properly and not like disposable trash.

Though I'd be curious how they're using AI.