Hi, As announced here, Slack and Teams are two both equally most popular communication tools. Though I personally used Slack, Teams is always my favorite. Which one is your favorite?
Discord is my favorite till now.
Discord is great because of the Voice Channels where you can hang all day and also can pull someone in a voice channel as admin.
Teams is very good for structured communication and is kind of a replacement of what used to be Intranet.
Con: Bad gifs databaseā¦ 
Slack is starting to lack a little in modern features and the UI has not been updated in years.