When comparing Messenger vs Element (formerly Riot), the Slant community recommends Element (formerly Riot) for most people. In the question“What are the best messaging apps for Android?” Element (formerly Riot) is ranked 2nd while Messenger is ranked 21st. The most important reason people chose Element (formerly Riot) is:
You're not confined within Element's or even Matrix garden, and you don't have to make users of other networks switch to Matrix.
Specs
Ranked in these QuestionsQuestion Ranking
Pros

Pro Uses Facebook friends to create a contacts list
Allows communicating with anyone who's a friend on Facebook.
Pro Read receipts
Can see who has seen each message in group messages.
Pro Easy to share posts from Facebook
Integration with Facebook makes it easy to share any interesting posts from the Facebook timeline.
Pro Great UI
User interface of the application is clean, intuitive and easy to overview.
Pro Bridges to other networks
You're not confined within Element's or even Matrix garden, and you don't have to make users of other networks switch to Matrix.
Pro Markdown support
Code snippets in chats can be highlighted with Markdown.
Pro Simple interface
Element has a very simple interface, adding the ability for more inexperienced users to use it.
Pro VOIP and Videoconferencing
Pro Supports encryption
Element allows for fully encrypted text, voice, and video chatting.
Pro Widgets support
Want to watch that flick at YouTube and discuss it at the same time? Have Grafana graphs stacked above your DevOps team chat? Collaboratively edit Google Docs and chat over without switching applications? This is possible with Element.
Pro Decentralized
An open network for secure, decentralized communication.
Pro Self-hosting and federated network
Pro Libre/open source
Pro Search
Search messages in your current room, or all the rooms you're in. Not subject to a message history limit like Slack.
Pro Cross platform
Web browser
Linux
OS X
Windows
Android
iOS
Pro Large existing community
With public rooms for many people, and you can create your own and let people from the community join.
Pro Etherpad real-time document collaboration
An easy to activate integration that allows multiple authors to edit a document simultaneously.
Pro File Sharing
Pro Supports text, voice, video
Cons
Con Lack of privacy
Messenger is owned by Facebook. Based on their privacy policy, this means that any information you provide (including messages sent) are used by Facebook to profile you and sell access to your data to advertisers.
Con Lack of end-to-end encryption
Secret (end-to-end encrypted) chats are only supported in one-to-one messages, and are not enabled by default, and the encryption has not been verified independently.
