There are plenty. Telegram and Signal to name but a couple. All encrypted, and much better with regards to user privacy and data security then any Facebook-owned entity.
it’s a very good app. Lots of users, easy to use and effective. It’s great for so many reasons.
It's not really a good app, and I can list down many reasons why Telegram is better. But like @Dracula said, it isn't a matter of which is better (because WhatsApp will never win that battle), it's merely a case of user base. WhatsApp was first on the scene and has the most users. Everything that came after (like Telegram) is better but has a smaller user base, which gives people reason to hesitate and make the switch. Telegram is still growing though, thanks in large part to WhatsApp's own blunders.