The best chat software for Linux, macOS and Windows isn't Slack

Everyone chats. Everyone chats with different apps and services. But which is the best? You might be surprised at the conclusion Jack Wallen draws. Finding the best chat software is a complicated mess. Why? Because everyone and every company uses a different service for team collaboration, messaging and even chatting with clients/customers. Some use Slack, others use Hangouts or Microsoft Teams. You might prefer Android Messages or iMessage. What about Twitter or Facebook messages?