Both JIRA and YouTrack have free-for-open-source licensing options we could apply for (linked).

Haikal has mentioned on another thread https://waffle.io as a nice value-add to github issue tracking.

In Ted's thread about development practices, we've mentioned some top-level Apache projects that link to design docs on JIRA issues, where the team iterates/comments on that one document directly instead of forum-style comment/reply communication, while preserving that option via the JIRA issue itself. Of course we have gitter for more interactive discussion, but the clarity a document with history of revisions and comments will provide is certainly worth it to me for the big stuff - could we achieve a natural integration of this on github's issue tracker without the overhead of outsourcing issue tracking to another platform?

I certainly like the idea that all the issues are actually part of the repo, so IMO the benefits and must-have features provided by an alternative to just using github would have to be substantial and exclusive. I would like to ask everyone if they think we should switch, and if there is enough of a split, we should then separately from this discussion vote on the matter. WDYT?