Discord for me. A bunch of my family and friends are avid gamers. Discord is the universal standard app they all use for general communication.
Not only do they use it for all their gaming related stuff, they have additional servers and channels for just chilling, chatting, off topic stuff, memes, politics, etc etc.
It's the network effect. Even if there was an open source app that perfectly replicated all the functionality of Discord and was just as simple to install and run as Discord, most of them still wouldn't switch to it, because all of their friends and family are still on Discord.
So they would have to have two completely separate apps with totally separate social groups to maintain, and nobody but hardcore advocates for FOSS and privacy are willing to do that.
Sure, I have Discord, Matrix, IRC, Signal, XMPP clients, and a Private Mumble server, all on my systems, but I'm hardcore about FOSS. None of my friends and family are willing to do that. It took all my energy to convince two of my most techie friends just to get Signal on their phones. And only One has been willing to install a Matrix client to chat just with me.