Exchange, Outlook, Teams, OneNote, Sharepoint are commonly used in such an environment, followed by Forms (HR department loves these and rightly so), Onedrive and PowerBI
Having worked and working with many of these:
Exchange is like poor man’s IMAP - it sucks in that it’s a closed ecosystem excluding non microsoft apps for emails
Outlook is worse than Thunderbird by far
Sharepoint is a clusterfuck of content management, especially(!) with in-website office document editing
Onedrive is only deemed “useful” because it is forced on people to share files e.g. in Teams, and because it is integrated into many IT environments to store homefolders etc. In effect, it’s a giant piece of spyware were users store their data in “clouds” that secret services will happily tap into
Teams is godawful in terms of UI - it’s decent conferencing, but so is matrix, with a much better chat interface / more flexibility for the user
FOSS office products have been far superior to what’s available on windows for at least a decade. There’s certainly occasionally one or the other app on windows that may shine in one aspect or two, but overall the bloatware user experience on windows is killing productivity of anyone who knows how to operate a keyboard.