I use Slack for personal projects and Teams for work. I think both are fine. The main reason it made sense to use Teams at work was because there were a number of products in use by different teams. IT had Slack and the rest had Zoom. Zoom was raising their costs and we already had Teams as part of 0365. So it was either buy Slack licenses for the entire company or just get everyone on Teams. It was kind of a no-brainer and it was hard to come up with a convincing argument to pay for Slack for everyone other than "Microsoft bad".