When comparing Jitsi vs Facebook Messenger, the Slant community recommends Jitsi for most people. In the question“What are the best Skype alternatives?” Jitsi is ranked 25th while Facebook Messenger is ranked 31st. The most important reason people chose Jitsi is:
Secure Jabber Texting, better than legacy sms texting.
Specs
Question Ranking
Pros
Pro OMEMO encryption without plugin
Secure Jabber Texting, better than legacy sms texting.
Pro Supports SIP accounts
well implemented SIP SIMPLE (texting), SIP presence, XCAP.
Pro supports XEP-0016, Privacy Lists
Jabber Texting apps without Privacy Lists are WOEFULLY deficient
Pro Video calls
Pro Encryption out of the box
Encryption for chat, desktop sharing, and web confrencing available.
Pro Cross platform
Mac, Windows & Linux availability.
Pro Open-source
Project available on github for anyone to contribute to or use.
Pro Chat head for quick access
Only for android platform though!
Cons
Con Abandoned android development
They switched focus to Jitsi Meet client for android.
Con Uses Java
Not a native app, takes awhile to load.
Con Gui not as slick or streamlined as competitors
Con Cluttered user interface
Messenger has so many features accessible from one page that it is often difficult to find what you're looking for.
Con Not very customizable
With so many features in one app, it's very possible you might not be a fan of at least one of them. Too bad you can't disable anything in settings.
Con End-to-end encryption only in "Secret" conversations
If you want e2e encryption, you need to start a secret conversation.
Con Closed Source