You're right of course. We we should have a preferred order. Let's define conditions as something common like group chat. Let's also define backdoor as something that allows any non-group member to read the messages.

1. Signal: Open source with E2EE group chats. Best choice, let's use that.

2. WhatsApp, Proprietary with E2EE group chats. E2EE implementation might have a backdoor with some probability. Let's avoid it if we can.

3. Telegram: Open source client with no E2EE group chats. The implementation leaks all group chats to server and anyone who hacks the server, and there's nothing we can do. It's backdoored by design. Let's avoid it at all costs.