Could you elaborate? I am using Telegram not because of privacy concerns but because of the desktop and tablet clients. I had absolutely no issues so far.
* chats not end-to-end encrypted by default (only secure chats), so clear text is on their servers
* group chats can't be secure chats
* the crypto is somewhat unconventional. While the developers had their reasons (constraints of mobile platforms), and no exploit has been found so far, AFAIK, any self-rolled crypto is a bit of a red flag to cryptographers.
* I have no reason to distrust Pavel Durov or his motives, but I am somewhat skeptical of services based in Russia (also, just to be clear, of services based in the USA or other five eyes).
To me, Wire might be the best of both worlds (as I've said in another post in this thread, and BTW I am not connected to them in any way):
Signal protocol; based in Switzerland; smartphone, desktop and web client; free; text and voice chat and group chat; open source (GPLv3, and on github); signup with phone number or email.
the desktop client was not encrypted at all last i checked, only the mobile client.
signal is e2e encrypted, it's in a completely different ballpark