I support good alternatives to Signal that also have other goals in mind. Signal's goal is to become basically as mainstream as Whatsapp is, and to get there it needs to make a few compromises for usability's sake.
Whatsapp has already backtracked on some major privacy promises, and who's to say it won't backtrack on the end-to-end encryption support eventually, after everyone is baited and switched to it? Or worse, it could start to decrypt E2E communications in secret for governments.
So we need a "mainstream" alternative that's actually trustworthy and can at least protect the security of the communications, if not the relationships between users.
However, I support applications that aim to offer even better privacy and security compared to Signal, that are aimed at more opsec-sensitive targets, such as journalists. Signal may be the best tool journalists have right now, but it's probably not the best one they could have, as it doesn't do a great job at protecting sources. Perhaps Ricochet or the Tor Messenger may be better for that.
What I'm worried about though is that even if these apps offer better security/privacy features, the various federated applications that use an E2EE protocol may not have too much of a security mindset. For instance, sure, Riot may adopt a better protocol, but is Riot itself using all modern security best practices? Can we trust the Riot developers just as much as we do the OWS developers? etc
Finally, I'd much rather see Signal become a P2P application than a federated one, if that would even be possible.