Telegram doesn't use end-to-end encryption by default and likely never will. Paul Durov has been quite hostile against that feature in the past. So yes, choose Signal over Telegram.
I find that instead of trying to convince friends/family to use Signal I just tell them "use Signal as your default SMS app" or install it myself for them. This tactic worked well in the Internet Explorer/Firefox and then Chrome transitions, so I don't see why it can't work again.
Then whenever I will be chatting with them, it won't matter if they try to send me a SMS, as long as I use Signal, their messages will be encrypted, as they will be data messages. I wouldn't trust the default SMS app/Android Messages not to steal your SMS texts anyway, especially on Chinese phones.
Also, I can't wait until the Matrix-based Riot gets its redesign:
The problem with that is assuming they will have internet connectivity always on when you want to contact them. Which I never found true even for the few people I regularly communicate over Signal. Most people turn off data and only turn it on somewhat regularly over the day to check stuff. Older people (like family) have no idea or barely know what internet is or even the button for that does and just expect communication to work like always: sms and phoning. But if people cam do the above approach good for them. I can barely convince anyone, even tech people from work or friends to install even more chat clients/services. Most are just fed up and feel tired of the whole thing.
To save money, battery and potentially protect weird apps trying to abuse the use of internet on background. Have heard and seen so many justifications for it. Barely know people that have internet 100% of time on. Somewhere in Europe ;)
I would to those following it that this advice is likely most useful if your family members are on Android devices.
iOS does not allow you to change the default SMS application and if your family member is on iOS, the iMessage platform lock in is nearly impossible to break out of.
I find that instead of trying to convince friends/family to use Signal I just tell them "use Signal as your default SMS app" or install it myself for them. This tactic worked well in the Internet Explorer/Firefox and then Chrome transitions, so I don't see why it can't work again.
Then whenever I will be chatting with them, it won't matter if they try to send me a SMS, as long as I use Signal, their messages will be encrypted, as they will be data messages. I wouldn't trust the default SMS app/Android Messages not to steal your SMS texts anyway, especially on Chinese phones.
Also, I can't wait until the Matrix-based Riot gets its redesign:
https://medium.com/@RiotChat/a-sneak-peek-at-a-whole-new-rio...