Slack offers quite a few features over HipChat that make it a nicer platform to communicate on, particularly for discussions of a technical nature. Things like

Slack offers quite a few features over HipChat that make it a nicer platform to communicate on, particularly for discussions of a technical nature. Things like easy message editing & markdown formatting make it easier to paste scripts, log messages, console outputs, etc. HipChat was fine as a bare-bones text chat. Slack is a pretty clear winner when it comes to a collaboration platform.