Instead of trying to figure out which messenger provides the best “security” features by certain technical standards, think about precisely the kind of security you need. https://www.eff.org/deeplinks/2018/03/thinking-about-what-you-need-secure-messenger
Thinking About What You Need In A Secure Messenger

All the features that determine the security of a messaging app can be confusing and hard to keep track of. Beyond the technical jargon, the most important question is: What do you need out of a messenger? Why are you looking for more security in your communications in the first place?The goal of...

@eff True. I'd also like to be sure that the main developer team has ethical intentions. I don't want a messenger that will be sold to BigTech some when. I don't want a messenger that in anyway spies on me. I don't want a messenger that makes me I fully dependent on a central infrastructure. I don't want a messenger that locks other implementations out.

This is just another definition on security.