Sooner or later, in my humble opinion, the next upcopming app is Telegram. I love signal too but my vote is for Telegram. Telegram is more than equal to whatsapp, it's far superior in many ways for example the ability to totally erase 'sent' messages even days or weeks asfter sending (on the recipients devices as well), better emoticons, tons of features, the ability so send longer video and Audio files etc etc etc - did I mention , MORE INTUITIVE over all? There are too many features to list here. Disclaimer: I don't work for Telegram.