Definitely I think its between Telegram and Signal. With Signal, there is definitely that comfort level of knowing that your information/chats are secure, but I have found it to be slightly less user friendly in terms of setting up chats/group chats etc. Its also not as widely used compared to Telegram.

With Telegram, I have been using it more recently and found it to be even effective in a work-setting for group chats, sharing files etc. Its basically a Slack and the fact that it is available on multiple platforms also has made it very appealing.