RedViking
Nord of the South
Discord and Telegram.
Discord also has a quick screen share option like Skype, which was the main reason I stayed with it, though I do use Team Viewer often enough now to permanently have it open. Sound quality seems to have also improved on Discord (or at least other people's microphones...).
The Discord overlay in games is still great if you have a 4+ person group, it's also good for work chats as we can separate everything into different channels (also seems to use a heck of a lot less resources then Slack, which just kept getting laggier and laggier even though we all have quite beefy machines, especially when we had more than one workstation).
For "mass" presentations where you don't want to be interrupted by others but still want to interact via IM, Team Viewer meetings is great, otherwise use YouTube's ultra low latency but I find that still has ~3-4 seconds of latency as we don't seem to have good servers in South Africa (in Austria I had maybe a second delay?).
I'll check it out. I like what they did here:
