Neither of those look as good as Slack imho. Regardless, there's a bunch of stuff you can do with Slack that you can't with IRC. Emoji reactions, voice/video/screenshare, easily post files and images... Plus there's a unified experience for all users that's not client dependent, no burdensome technical or protocol jargon, no federated servers (or servers to think about at all)...
I've used IRC quite a bit but Slack is light years beyond in terms of the UX of even the nicest IRC clients. I think Discord is probably even better than Slack though.
I've used IRC quite a bit but Slack is light years beyond in terms of the UX of even the nicest IRC clients. I think Discord is probably even better than Slack though.