Hello, which privacy and anonymous messengers would you consider to be best? Again which of these would work best with TailsOS?
Tails is not an OS you normally want to use with E2EE IMs. But if you must, the only one I can think of is the feature built into Onion Share. But I doubt you can keep that in persistent storage for your needs.
Or you can always self host Matrix or sign up for XMPP anonymously and use that with OMEMO encryption with a web based client (which may or may not be best but it is a valid option nonetheless)
Generally Briar, SimpleX if not for matrix and XMPP, both use the onion network. I cannot comment for OnionShare but should be an option.
I use the built in Pidgin with tails and remember the accounts details in my head
I think an XMPP app is part of the OS so they seem to be pointing users to that.