As far as possible I try to avoid:
-
All things from big tech because privacy, see Schrems II and their terms on use of personal information for own purposes
-
Non Open Source tech because privacy or other malicious functions
-
Tech that are prone to planned obsolescence because of special batteries etc. and can’t be fixed with for example a custom ROM on Android
XMPP / Jabber with OMEMO encryption. Lots of free servers and clients.