Signal. Telegram is a business run by a millionare who is having fun. Signal is run by well known security expert / activist and his very transparent company Open Whisper systems.

The way Signal tackles the problems is smart gradual development and they are the closest to making the holy grail - e2e encryption without users even noticing it. There are no "secure" and "not secure" messages in signal - it is all encrypted and you can't turn it off. That's awesome.