Messaging is in a poor state these days.
- SMS is unencrypted
- WhatsApp is proprietary software owned by an advertising company
- Telegram tried to roll their own crypto
- Signal is completely centralized and could roll out an update breaking their encryption at any moment
- Jabber doesn't seem to support E2E group chats and doesn't have any reliable free providers
- Email is slowly being replaced by Slack which itself provides no encryption AFAIK
- Matrix E2E is in beta