JIRA is just fine. Can't really go bad with it. If you have limited needs, you can try GitHub or GitLab Issues. But for a team which may end up growing, JIRA will work. It has good integration with GitHub/GitLab, and with Smart Commits enabled, most of workflows can be baked into it. It's slow, but judging by this thread, I suspect Atlassian customers are complaining about it too, so hopefully it'll be heard.