"Hero" has always referred to the hero the enhancement is played on (i.e. "[This] Hero"). I see no reason why "OT Hero" would not be ruled the same. The only time you get to choose is if the card says "A hero" or "One hero" (for example).
With that said, I agree that we need an official Play As/Errata to distinguish whatever decision is made, since this is a common inconsistency in rulings. Putting that "OT" in the front was awkward.