I do still use whatsapp but it's almost a necessity and I feel that there's more safety in that.
There are many other open source and end-to-end encrypted instant messengers you can use, but I appreciate the problem is getting all your friends/colleagues/whoever to use them too.
Signal is the one I use. It is free, open source, and available for in android, iOS and desktop versions. It also supports voice, image, video and file sharing. There is also
Wire which pretty much does the same things.
I use Signal but unfortunately the only people I know who use it are people in the cannabis industry (or otherwise involved in black or grey market activity). It's incredible how egregious the privacy violations are with major social networking apps, but nobody seems to care. Most people I talk to have no interest in using Signal. Messenger still seems really popular.