Dennis from TestRail here. I thought it might be useful to know why we have many teams regularly migrating from basic JIRA add-ons to TestRail and there are various reasons teams migrate to or choose TestRail.
TestRail offers the best of both worlds: a fully featured test management application that provides all the features needed for teams to be effective and productive. And at the same time we have a rich JIRA add-on integration to view linked results, test cases and reports inside JIRA. TestRail is the only application offering this kind of combination, and because of this we have a lot of teams switching to TestRail every week.
We also have many teams migrating from the various available basic JIRA add-ons, as they usually don't support even very basic features required for teams to be productive that you can find in a full test management tool (e.g. very basic things like grouping tests in sections, maintaining test orders, reusing tests easily, running tests against different platforms such as browsers/OS/platform configurations, rich automation APIs, forecast reports etc). E.g. TestRail's FastTrack interface alone helps teams save a lot of time every week:
You can learn more about other features why teams switch here, so you can use this for a comparison matrix you mentioned, as well as our rich JIRA integration that supports full coverage between requirements/use cases in JIRA, test cases and test results in TestRail, as well as defects/issues in JIRA:
TestRail is also in the very unique position that we fully support both JIRA Server and JIRA Cloud, and TestRail was even featured for this on the Atlassian/JIRA blog:
I hope this helps!