What is better, powerstancing katanas or 2 handing a katana?

And which katanas are better?

This is my first playthrough and I have no idea what I'm doing. I'm interested in focusing on dexterity primarily and in using katanas.

The problem is I don't know what would be the best to aim for in early game and in later game. Right now I'm at godrick and got smoked so I'm here.