There are varying opinions on that, some based in facts and some less so. There is research about the relative security of each.
In the short run for most people, the answer is probably "the one that you know other people use that you want to talk to.
I used Telegram for over two years because I chatted with someone and we wanted to be sure if privacy. Now I don't know anyone who uses it. I downloaded Signal recently because it can replace my regular SMS text app. I don't know anyone else who uses it.
There are varying opinions on that, some based in facts and some less so. There is research about the relative security of each.
In the short run for most people, the answer is probably "the one that you know other people use that you want to talk to.
I used Telegram for over two years because I chatted with someone and we wanted to be sure if privacy. Now I don't know anyone who uses it. I downloaded Signal recently because it can replace my regular SMS text app. I don't know anyone else who uses it.