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"Best" is relative. I'd say the best one is that app which most if not all of your friends are currently using. What's the use of using a "nice" messaging app if you're the only one using it?
For example, I have Telegram - quite a nice app, one of the first with end-to-end encryption, but it was introduced to me by my girlfriend. Now I use it exclusively to communicate with her and her alone. Can I use it to communicate with other friends? Yes... if they all installed it.
There are many to choose from and majority of them provide all the basic functionality of a communication tool: chat, call, video message, "emojis", such as Line, Viber, WeChat, Skype, Messenger, WhatsApp, Telegram.
Go for what your friends are using.
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