I know the title of this blog will raise some feathers, but please finish reading my post before assuming this is a critic without balances observation.
So, to clear some points up, I do not mind the Atlassian tools, don't get me wrong there's no real replacement for Jira, Bitbucket is also a alright offering however with that said, Atlassian's chat tool is in my opinion is outdated.
Ok if you consider their competitors I assume the obvious comparison would be Slack. Now Slack offers the similar developer apis a active community and in my opinion a much for clean cut option, Hipchat web interface feels clunky & methodical. Moving from slack to hipchat feels like going from WhatsApp to MSN Messenger, it's just gives you the sense that this is nothing new, it's something I might reminisce on, from back in my teenager years, probably whilst fighting through the glare off a CRT monitor.
It seems silly, for this corporate tool it is nothing more then a slightly more open version of Lync, the chat groups and conversations stack in a boring unimaginative way, whilst the search via the app returns anything that partially resembles the search and doesn't prioritise conversations you was actively involved in.
Then there's the app problems, Mac client is a complete waste of space, to this day it's never connected to the team server correctly even though iOs, Windows clients seem to work seamlessly.
all in all, I believe it offers little and charges allot for the privilege.
I think Stride is the answer on this, however you will need to give it some time, they spent time on getting the UI and UX better, but now it is waiting on some functionalities and integrations...
What are you expecting of this client? For its purpose HipChat seems to do fine for us. I'm not happy with HC server being moved to data center and requiring a subscription such as AWS to just use it. I want to self host on my servers and not have added costs. But that's off topic for this discussion on what HC's purpose really is. Maybe if you want to call it out for not meeting its purpose consider outlining your objectives and design goals for an app/client such as this?