Signal Private Messenger
Privacy is possible. Signal makes it easy.
Actually… it's arguably the only secure one since it's on by default (versus the likes of Allo and WhatsApp where you have to specifically enable it).
Signal has already offers the best way to send secure and privacy conscious messages (and voice calls) on Android and iOS. Now everyone can use Signal on the desktop as well. The desktop app can import your contacts from Signal on your phone and keep your messages synced.
If you already have the app downloaded, just head to https://whispersystems.org/desktop to download the Chrome extension. Then simply point your phone camera at a QR code for setup and you're done.