@paulfree14 @x0rz In terms of raw security, Signal's protocol is best but they do have the ability to add devices to an account, Australian-spy-style. But it will at least warn other users about "safety number changed". I overall recommend Signal, even though it's centralised and doesn't federate. XMPP's protocols look strong if used correctly.. but "used correctly" is always the failure point. So I'd never recommend to my tech-fail family.
@paulfree14 @x0rz Briar is fairly new on the scene, so I'll remain cautious for a while. And, it's hard to model threats in P2P, there is usually a trade-off. Take Fediverse as an example: despite being free of overt, "legal" surveillance capitalism, the Fediverse generally is easier to crawl and monitor than, say, Twitter or Facebook. So illegal or covert surveillance is substantially easier here.