I know that a lot oft options are close and make different trade offs. But as you said yourself. The fulfill most criteria not all.

At least matrix doesn’t let you move your account to other server. Also it doesn’t minimize metadata storage. Its is stored on every server for a room.

The other two I don’t know. I’ll look them.up.

The perfect messenger would be open and private.

That means open source, federated with portable account’s, e2e encrypted, minimal metadata storage, discoverable contacts, easy to self host as compute, storage and knowledge.

That doesn’t exist as of today. Also it’s really hard.

Pretty much everything is better than WhatsApp though.

Cursive was added later or modified to clarify.