M365 family doesn't let you manage users as part of one "organisation" in the same way that Google Apps does. It's effectively 6 copies of M365 Personal. And you can only add a vanity domain if you happen to manage it with GoDaddy. The closest to G-suite is M365 Business Basic which is cheaper than G-suite and only includes web and mobile versions of the Office suite, but it does come with 1TB of storage per user which is nice.
As someone else mentioned - the cheapest per user hosted service that is close in functionality to G-suite is Zoho.
I know all this because I've also been bitten by the impending decommissioning of free G-suite so did a bit of research yesterday. I've signed up with M365 Business Basic and am in the process of moving my domains over to it now. I only need one mailbox but I have a bunch of domains and email aliases that I manage.
As someone else mentioned - the cheapest per user hosted service that is close in functionality to G-suite is Zoho.
I know all this because I've also been bitten by the impending decommissioning of free G-suite so did a bit of research yesterday. I've signed up with M365 Business Basic and am in the process of moving my domains over to it now. I only need one mailbox but I have a bunch of domains and email aliases that I manage.
(edit - changed "Starter" to "Basic")