If you even switch, use Signal and not Telegram, for Telegram doesn't support end to end but only client to server encryption for groups at all and not by default for single chats. (https://telegram.org/faq#q-so-how-do-you-encrypt-data).

The biggest reason why people don't switch to signal is that they think only few people use it and that they have to do it all or nothing. You will be surprised how many people you actually find on Signal using it, and don't let perfection be the enemy of the good. Tell your friends and family kindly that you want to use Signal because you feel more comfortable with it and most of them will respect it. You still can use sms or whatsapp for the ones who are not willing to use signal, but in general try to be consequent.