nice guide. simplex is recommended in our guide and most others' as it passes our strict guidelines for inclusion.
i have had multiple conversations with evgeny since we started testing and using simplex ~a year ago. i even helped onboard him to nostr.
there have been growing pains since alpha/beta (voice used to just not work) but as with any app/protocol, development has come a long way since then and they are quick to squash any bugs.
they are open source, e2ee by default, support e2ee for all messages and they have been sucessfully audited.
the only remaining bonus metric afaic is to be battletested in court and that comes with time.
https://simplex.chat/blog/20221108-simplex-chat-v4.2-security-audit-new-website.html