When comparing Messenger vs Keybase, the Slant community recommends Keybase for most people. In the question“What is the best team chat software?” Keybase is ranked 25th while Messenger is ranked 74th. The most important reason people chose Keybase is:
Completely end-to-end encrypted.
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 E2E encrypted
Completely end-to-end encrypted.
Pro Identity verification
Users can publish proofs of identity (PGP public key, Twitter, Facebook, etc).
Pro FOSS
Free (as in beer) and Open Source Software.
Pro Encrypted file sharing
Securely share files.
Pro Public encrypted filesystem
For sharing files publicly.
Pro 250GB of free team file storage
250GB of free storage for encrypted files in a team.
Pro Public teams
Teams can be public with open access or admin-approved access. Opt-in to list public teams.
Pro Private teams
Teams can be completely private (access granted via admin-approval only, not publicly listed).
Pro Encrypted Git
Encrypted private or team Git repositories with automatic commit signatures.
Pro Blockchain technology
Based on blockchain technology.
Pro Sigchain verification
View/verify the cryptographic signature history of any user.
Pro PGP/GPG support
Encrypt/decrypt any PGP message or file with minimal effort.
Pro Public key encryption
Supports public key encryption.
Pro Private encrypted filesystem
Securely store personal files that only you can access.
Pro Shared private encrypted filesystem
Share files securely and privately with other users, a group of users, or a team.
Pro 250GB of free private file storage
250GB of free storage for privately-encrypted files.
Pro Free static site hosting
Host a public static website for free. Sites are automatically viewable via keybase.pub if an index.html or index.md exist in your public files.
Pro Emoji reactions to limit excessive posts and notifications
Pro E2E encrypted team chat
Teams are E2E encrypted, unlike Slack and other services.
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.
