I have a private, premium slack with ~20 of my closest friends from college, which I set up in March when we all were sent home from campus. It replaces many many disparate group chats and fits our need for customizable text-and-image chatrooms, voice and video calls, and support for mac, windows, linux, android, and iOS, with machines of vastly different levels of power and quality (although it could be a little more lightweight to help out low-tier computers).