I use #XMPP as my sole means of communication (public channels, private groups, private messages, and calls), and consider it to have better foundations than #Signal, #Telegram, and the rest.
For most people, I recommend #Quicksy or #Prāv, which use phone numbers for easy onboarding.
More privacy-conscious people can choose clients and servers which don't require phone numbers. Technical people can self-host private servers using #Snikket, or use paid hosting.
I've written a guide for new XMPP users here -
https://contrapunctus.codeberg.page/the-quick-and-easy-guide-to-xmpp.html
