Microsoft Teams

Teams organizes around a Teams-then-channels hierarchy that mirrors org charts, which is both its logic and its burden: the nesting is tidy on a slide and confusing in daily use, since a channel's files, chat, and tabs live in separate planes. Its real center of gravity is the calendar and the meeting, with chat often feeling secondary to the join button. The left rail crams Activity, Chat, Teams, Calendar, and Calls into one column, and the reply model favors a per-post thread that keeps conversations boxed but makes fast back-and-forth feel stilted. Deep Office and SharePoint integration is the genuine strength, letting a document open and co-edit in place. The recurring complaint is heft: notifications fragment, and the app can feel slow and overstuffed.