User blog comment:Uraharattack/Starrk's classification as a hollow?/@comment-1387259-20130820163125/@comment-11051098-20130820193826

I believe you're right. All the original Espada including the Privaron Espada most likely were Arrancars by their own power.

The exception is Aaroniero, who was a Gillian until his death despite his power and rank as an Espada.

I suppose Aizen increased the power of some or all of them, though, given Nnoitra's words in a flashback, where he was sitting on a rock somewhere in the desert of Las Noches thinking to himself "if I was to be grateful to lord Aizen for anything, it would be for making me stronger".