Microsoft ecosystem
For what time I've used potonmail I completely love but when you're embedded into their ecosystem as much as I am it's becomes hard to come off.
What makes the decision to leave Microsoft hard is not been able to use AMP e-mailing system on proton and not being able to sync my contacts and calenders to my Samsung galaxy phone even though these features are on proton mail and proton calendes I prefer to use the Samsung galaxy default apps like I have gone with my outlook account.
Even though there's a third party out to do this is it worth it that is the question
email wise definitely
calendar and contacts not so much