The problem with this question is your friends, if whatever you decide on isn’t something your friends have or are willing to get, then it’s not useful for you. Signal offers probably the best mix of adoption and security. It however misses a few notable features, for example the iOS client has no way to back up or restore your messages. I’m a big fan of matrix, which seems very extensible and has good security, but if you are in a sensitive application like an authoritarian country, it wouldn’t be my choice. All the messages are stored on the server and while they are encrypted it’s still not what I would use for a chat I never want to see in court.