Here's my feedback. As a part of a small startup team, I used Jira for years before Github issues and Slack were there.
The company I work at right now still uses Atlassian's trio Jira + Hipchat + Bitbucket. They are great tools with lots of features but Jira's productivity is much slower compared to Github issues and Hipchat offers a poor user experience compared to Slack.
The company I work at right now still uses Atlassian's trio Jira + Hipchat + Bitbucket. They are great tools with lots of features but Jira's productivity is much slower compared to Github issues and Hipchat offers a poor user experience compared to Slack.