I still reckon Cora is the QoH, actually even moreso since seeing her pull that trick with Daniel’s heart. I got to wondering that was like her own patented move she’d come up with, like her trademark way of offing people, by tearing out their hearts.
Also, for what it’s worth, if you follow the Latin translation for name meanings, like Regina translates to queen, well, heart translates to cor. And heart in Spanish is corazon. So if Regina is the Evil QUEEN, then it makes sense to me that her mother Cora would be Queen of HEARTS.
Though I did like the idea that Regina got her powers by killing her mother, because Rumple told Charming that if Snow killed the EQ, she’d become as evil as the person whose life she takes. But I could still see that theory working in a similar way if Regina finds a way to steal her mother’s powers and then banishes her to Wonderland. Actually, stealing her powers would explain why Regina can do the same trick with removing hearts.