If you want your organization to have frustrated employees dealing with software that was created decades ago and has only received patches and cloud services bolted on, highly inconsistent UI/UX, way too many irrelevant features thrown in your face and essential features hidden behind a layers on UX, I can highly recommend for you to invest in Microsoft Office and Teams.
Teams fails to do very basic things right and is a nightmare to use and administrate.
If you compare Teams to Slack, I wonder why companies still choose Teams. The only reason must be the fact they are already bought in to the Microsoft ecosystem and Teams comes practically free, whereas Slack would not.
Regardless, Slack in combination with Notion and/or Google Suite is still the better option, because these are so much more elegant and light-weight. These tools are not in your way but work with you, even though nothing is perfect of-course.
I have a deep hate for Microsoft software, a hate that bubbles up from the very core of my human existence. Microsoft is still successful only because of legacy, not because of the quality of their products. I will never, ever allow this junk in my next company. It’s the death of productivity and a pleasurable working experience.