wanna explain how you misinterpreted such a simple question?How is that even relevant?
The question is "most powerful water style user?" - this to me is asking who is the most skilled. If we're talking about who has the most powerful water style techniques, that is a different story. If the OP is asking from a techniques point of view then your right.
If none of her technology can get past his techniques wouldn't they mean his techniques are the most powerful?
Food 4 thought.