Actually, it sounds small, but the biggest advantage of HipChat over Slack is that HipChat allows you to change the background color of bot messages (like incoming exceptions, deploys, etc.). It is incredibly frustrating that Slack can't allocate an engineer to just do this. Slack's custom message styling options are virtually nonexistent. Yeah, yeah, I know we programmers shouldn't say "it will only take a few minutes," but come on!