I'm always the desenter. I definitely think Harry is the most powerful wizard. Dumbledore couldn't defeat Voldemort. Dumbledore never survived a killing curse.

Harry is the Christ-like figure in the series. He was protected because of love. He has a wand with a phoenix feather from the same bird as Voldemort. The only difference between him and Voldemort is his choices. He's good and makes good decisions.

Dumbledore knew a lot from his experience and learning, but Harry can has the potential to become a lot greater than Dumbledore simply because his capacity is greater. Who has more power... Harry. The unforgivable curses have less effect on him. It's a natural ability, not a studied ability, essentially it's like magic itself.

Muggles can't learn magic, because they don't have the ability. In a magical sense, Dumbledore became as great as he could because of his abilities, but Harry has greater abilities. Harry just has a lot of book learning to do.