>the only better alternative would be self hosting.
Which doesn't really work in practice. The closer you move to the user, the more the threat of creepy buddy watching over metadata of people they know grows. Medium sized institution like university or a company might run their own, but that's also somewhat risky.
>the question is not what is the best, most secure, most private, option, but what has the right balance between easy onboarding, ease of use, security and privacy.
No. The question is, given an architecture that imposes fundamental limitations on what can be achieved, which tools under that domain have best privacy by design system, where the UX and features are maximized with ingenious design, is the best.
Fundamental architectural limitations:
Does Delta Chat use data diodes? No? Then it can't have key exfiltration security, but it can have message forwarding.
Does Delta Chat use Tor Onion Services? No? Then it can't have proper metadata privacy for users' identity from the server, but it can have offline messages.
These are fundamental trade-offs.
DeltaChat is content-private by design. It might be metadata-private by policy (internal policy that server on nine.testrun.org does not collect metadata), but until that is tested in court like Signal is, we can't know for sure.
Signal is content-private by policy. Cwtch uses Tor Onion Services so it's metadata-private by design.
Now, it's fine to argue which is the best inside one league.
Element/Matrix is E2EE with double ratchet protocol, so it has both forward secrecy and future secrecy, which DeltaChat doesn't have.
It's only once security is more or less exactly on par, that you should be comparing general UX. Really usable but insecure tool might turn into really unusable tool when you sit in prison for your political opinions, or because you revealed your ethnicity and ICE caught on.
>maybe deltachat is not the best possible, but it is pretty good
It's not the worst out there. At least it tries to do things properly. It's just that given that there's insane obstacle of moving people to a safe platform, DeltaChat is just another distraction. Until it does what competition does security wise, and improves on their UX, it doesn't get the top podium.
>when security and privacy are to onerous then you don't have security or privacy
Sure, but when you're in prison for using crap tool, you won't have liberty, security, or privacy.