Instant messaging is one of the things that the Internet makes really handy. I truly prefer it over conventional calling because it allows me to be asynchronously efficient. I can answer questions more accurately since I can quickly look it up and send it back to you. On my desktop, I funnel all of my instant messaging through three applications.
The Electron-based heavy weight holds a few team accounts I'm actively engaged in. I keep in Do Not Disturb mode a lot since it doesn't do a good job of respecting notification signaling on Ubuntu running KDE. I've tried using Slack from another client (WeeChat). As much as I did enjoying using things in the terminal, my personal ambitions with work encouraged me to move to more things that my ideal group of people would use. We about that point-and-click life!
The go-to client for IRC on KDE is Konversation. It's not the shinest tool on the block but it gets the job so well, I find it hard to use anything else. It's where a lot of my chatter on open projects go. I'm usually connected to Freenode and OTFC and use bridges for Gitter all from my ZNC instance so I keep my history and unseen machines when I disconnect.
More and more now, members and projects of the F/LOSS community have moved to use messaging systems built on Matrix. I was hesistant on using for some time because it seems like a re-making of XMPP but in JSON instead of XML and with none of the learnings of the XMPP community. However, trying it as a user and not a developer; the experience thus far is okay.
The experience here is cleaner but there's a bit of a mismatch in how icons and messages are presented. I opened up a ticket about that - easiest way to give back and help things that you use often! I do like that Quaternion is a native client that supports a lot of the features of Matrix - a proof that you can still use native (as in no runtime outside of your system's) logic to deliver value to users.