My team at work piloted using Mattermost before my company finally settled on Microsoft Teams company-wide. Something about Mattermost was just so much more engaging than Teams. People chimed in with answers and opinions on things way more. There was team bonding in the form of custom reactions and plenty of "off-topic" banter in the appropriate places. Teams just feels so dead in comparison. Maybe it's the way channels and notifications work. Maybe it's the lack of custom reactions. Maybe my team just had too much turnover. I don't know.