Nobody really likes Teams, but it does seem to have more features than Slack in terms of integration with the rest of Microsoft's office software ecosystem. It's nice to be able to open up and edit Word/PowerPoint/Excel documents directly, view the Outlook calendar directly, etc. It is also integrated with SharePoint and OneDrive for file storage. Teams had video calls before Slack as well IIRC.

Teams, Slack and Discord all seem to be built as clunky web apps; but my experience is that Discord seems to work slightly better than Slack, which in turn works slightly better than Teams.