[synicalx]

People like to jump on bandwagon or the other, but the real answer is - it depends.

With Slack, the application itself is probably pretty tough, but for a lot of businesses their infrastructure and connectivity TO Slack (ie internet/WAN) is probably not very resilient. So for a lot of smaller outfits I'd say that Slack is better.

But if you're a large org and your infrastructure is very resilient and diverse, then you're probably better off self-hosting - assuming you can leverage your existing infrastructure to do so.