What's the best Instant Messaging app for privacy?

So recently, I've been wanted to switch over to a more private messaging application. The top 3 recommendations are Signal, Session (fork of signal), or Element (or anything else that uses the Matrix protocol). All three of these have E2E Encryption.

Signal is open source, but the service itself is *centralized,* while Matrix and Session are not, and it also requires a phone number as an identifier.

I'm stuck between these 3. I *could* use all of them, but that …

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