I would say the lowest one.
The first one has odd blur, the second is nice and focused on the eyes, but you are missing the nose, the third the eye is turned away and you don't have the whole face in focus. The final one has pretty good focus and great detail, if you have any editing software i might work on the nose crustiest just a bit.
They are all very nice pictures and have good depth of field. My fiancee has taken some photography classes and she said focus on the eye is like the most important part of a portrait, I would say depth of field to be the next. Focus on the eye, but try to capture as much of the face as possible while you're at it.
Good Job!