After the whatsapp facebook aquisition many of my friends looked for something different. So they choose Threema and Telegram. Which are both horrible.
Please guys. Use TextSecure [0].
It would be nice if there was actually anything better than Telegram I could recommend to my friends, but there just isn't.
Even if you don't feel iOS devices are trustworthy, as long as it's limited to the Android-only world, it's not going to gain a wide adoption.
https://github.com/WhisperSystems/TextSecure-iOS
They also experiment with alternative currency contributions:
https://whispersystems.org/blog/bithub/
I think what I've never found is a honest description how much exactly we have to trust their server (on various levels, from the security aspects to the uptime aspects), and what would be the possibilities for involving other servers.
The people I communicate with are on iOS where there's no TextSecure client.
But the bit I dislike about TextSecure and whatsapp is that it's based on a phone number bound to the contactlist of your Google Play Android phone. I see a very strong movement towards kik messenger among my peers because usernames are so easy to deal with and share around in semi-public places.
Believe me, I would love to.
But I don't have an Android phone, and even if I did, not all my contacts have one.
The reason WhatsApp is so popular is exactly this, it just works and it works on all mobile platforms.[1]
[1] http://blog.textit.in/your-path-to-a-$16b-exit-build-a-j2me-...
That's really your problem though.
There might be iOS version, but there very likely never will be web version, or FxOS version or desktop version or anything like that.
Which is really sad, because unlike Telegram authors, TextSecure's author is very good with crypto.
[1]: it's a long read: https://github.com/WhisperSystems/TextSecure/issues/127
Threema seems to be using http://nacl.cr.yp.to/ for anything crypto related.
Regardless, if you think that way you can also not trust the TextSecure binary you've downloaded frome the Play Store nor the Android phone you're using.
I guess you've trust someone or start building your own hardware, mobile phone OS and instant messenger and make everyone else use it as well, otherwise there's no one to communicate with. However, those people will be in the same dilemma:can they trust you?