Define best.

Briar, peer to peer, through Tor, ISP can’t see meta data, no company owned central servers that can see meta data, eats battery like crazy, only on phone, professional development, no need for phone number.

Tox, peer to peer, no Tor, ISP can see meta data, no company owned central servers that can see meta data, eats battery like crazy, has a desktop client, there were issues with encryption in the past, no need for phone number.

Jami, peer to peer, no Tor, ISP can see meta data, partially centralized helper servers that can see meta data, eats battery like crazy except when helper servers used, all platforms, no need for phone number.

Signal, central servers, American, non-profit, needs phone number, issues with open source.

Wire, central servers, Swiss, backed by American venture capital, doesn’t need phone number.

Element(Matrix), federated servers, they see meta data, doesn’t need phone number.

Conversations(XMPP), federated servers, they see meta data, doesn’t need phone number.

https://lemmy.ml/pictrs/image/riLmLMwlQg.png

https://privacytools.io/software/real-time-communication/

Peer to peer gives the most privacy of data but eats your battery and can be buggy. If you just dislike surveillance capitalism and your messages getting snooped on for profit and ulterior manipulation, the centralized and federated servers options are just fine. Peer to peer might be overkill unless you’re a whistleblower or journalist or whatever.

There’s no one size fits all best.