None. I think like everything IBM, Microsoft, and now Atlassian, no-one ever lost their job by using Jira.

i.e. the masses have formed an opinion, Jira won't get you fired. Something else will, so if in doubt, use Jira.

Lot of people in doubt out there.

Indeed. I find that the vast majority of the time, their UX actually gets in the way of the power and configurability. Moreover, many things are overly complex, in the sense that you don't get anything back for the complexity introduced.