bbPress.org

In my opinion, a fair comparison would have to be WP/bbPress (deep integration) and WP/forumpluginX.

You’re wanting to compare an unsupported, unintentional, unadvisable, found-by-mistake hack (that doesn’t always work) against a theoretical piece of software. It’s a no-brainer which will compare favourably.

A fair comparison should be a WP/bbpress normal “as intended” integration to a WP/plugin.