I've decided to set up a monthly donation to the Signal Foundation. I'm not the biggest fan of Signal and I've been critical of the fact that it relies on central servers that can be shut off at any time.
But none of the peer-to-peer apps I've tried (such as Tox) seem competitive in this space. I need something I can give a non-technical friend and not have them feel like its a downgrade from WhatsApp.
For now I'm going to stick with Signal but I'll keep an eye on some other promising projects like Matrix.