ProtonMail is overhyping the "encrypted" email charade. 99% of the humanity doesn't need anything of that sort. Runbox was hyping on its "green credentials". I didn't consider it much thereafter. Hey.com has a cartoonish email interface and their play on the email service is interesting but useless. I couldn't take them seriously after poking around for 5 minutes. There are other interesting services (purelyemail) but that's in Beta.
Zoho was a major disappointment backed up by a poor customer support. Email sent to their support remains unaswered even after 12+ hours. I have requested them for a refund and is avoidable. I considered iCloud+ with a custom domain and Google Workspaces but I was concerned about lack of support on both services.
Fastmail offers everything. I have my configuration set up on iphone and works flawlessly. No issues with their mobile app or any restriction on their alias generation. I have unlimited Masked Emails generated through BitWarden as my password manager.
TL;DR Stick with Fastmail for peace of mind. It is expensive but offers complete value for money.
