I've heard more bad than good in both the Auburn and Eaton, so asking which is better would get you nothing more than a subjective answer at best. In an overall strength test, I'd buy the Auburn just because the clutch packs in the Eaton look "mickey moused." However, I'd buy the Eaton just because it's rebuildable. In all fairness, I've never seen any kind of Auburn product, so my opinion should not be taken for anything more than words on a computer screen.
Joe