I don't particularly like Discord (which I assume you meant) because I don't see a monetization plan for them that doesn't screw over their users. With Slack, I know that they have enterprise customers that essentially pay for the free users. Discord has nothing like that, and I can only foresee two outcomes: running out of money or selling out their users. Charging for their service won't really work, either, because gamers are a pretty price-sensitive group in my experience and Slack is still free.