You can motivate them saying them that, unlike WhatsApp (and iMessage ?), on Signal you can edit your messages after sending them and you can program messages to be sent (and you can finally edit messages but WA can too).
You can motivate them saying them that, unlike WhatsApp (and iMessage ?), on Signal you can edit your messages after sending them and you can program messages to be sent (and you can finally edit messages but WA can too).