I make a product management tool/issue tracker that integrates to both tools, and I will say from the perspective of a developer integrating to them, Slack is e

I make a product management tool/issue tracker that integrates to both tools, and I will say from the perspective of a developer integrating to them, Slack is easier to work with (though Discord is ok too). Little things like the "only visible to you" messages in slack make it much easier to make a nice integration.