I can't believe anyone would say that Teams is better than Slack.

Almost everything about Slack is better. It's easier to manage conversations/channels. It's easier to read. It's easier to write. It's easier to customize.

The only thing I've heard is that Slack is unstable for some people. I haven't experienced any stability issues in 3+ years using the MacOS app. I've heard that the Slack web interface may be the cause of stability issues.

We have Slack in my organization, but corporate has started using Teams for the past year. I think the writing is on the wall, and I'm dreading it.