Voted for Facebook messenger.

Nowadays I mostly use Facebook messenger to communicate with real life friends and relatives. Sometimes I also use e-mail for that.
Nowadays I also use SMS, but I don't send SMS. I usually read it.
I use SMS mostly to receive information from my current service provider (Vodafone), and I also use SMS to security purposes, for example code for internet banking, Facebook login, and for other things.
I also use Discord, but not primarily to communicate with real life people.
I mostly use Discord to use free upvote bots, or to promote my posts, or to request status updates from bots (for example my quota for dustbunny).
Nowadays I rarely use Discord to communicate with real life people.