Agree with the other guy suggesting Signal. It's basically WhatsApp, owned by non-profit so that it can't be sold to a for-profit. They've been subpoenaed and the only data they could provide for a user was the phone number that was registered, the first day that number registered and the most recent day the phone number contacted their servers.
I would suggest reading through their blog posts if you're curious about all the work they're putting into ensuring that they collect as little data about their users as possible. they truly are innovating in a field where nobody else seems to care about ensuring privacy first.
This does come at a cost to how quickly user-facing features arrive compared to their competitors, but this is because they think through where you may leak data and engineer a way around it before allowing a feature to go through. That said, at this point it's pretty much at feature parity with WhatsApp, so moving over to it would be a great time to do so.
