JIRA is awful, although admittedly we were a small team when we were using it for a project, which apparently makes it not the best fit. But I really like the other Atlassian products we use. HipChat works well, it's not quite as polished as Slack, but it does the job and it's been a lot more stable the last few months than it once was. Bitbucket is excellent. We moved from Github to Bitbucket a few years ago and never looked back.