Text Messages and iMessage are stored in encrypted backups in the cloud. If you are syncing to your desktop and you uncheck "encrypt backups" then anyone who has access to your backup could (in theory) grab the message history from the backup.
I never sync my devices to desktop anymore.
So as long as you are relying on iCloud backups then your messages are as secure as they are with WhatsApp, except that you won't have a sociopath like Zuckerberg with the keys to the vault. lol
This is incorrect. iCloud backups are encrypted with your encryption key AND Apple’s encryption key. How do you think they are able to turn your data over to the government when presented with a warrant, or a National Security Letter? They decrypt your backups and turn over the data.
WhatsApp IS more secure than Messages, and so long as Facebook hasn’t tampered with WhatsApp, everything the Zuckbot said was true.