I like the first compostion better. It's like a visitor just popping into your life unexpectetly. The larger empty space contributes to that feeling of surprise and spontaneity IMO. An interestng point by dBgrafix about flipping the image left to right. Because we in Western society read from upper left to right we somehow subcosciously expect our eyes to scan images like that. The fact that she is entering the scene from the opposite corner kind of adds to the feeling of surprise IMO. One minor point though, I sort-of wish that there was more hint of highlights in the eyes and less on the earrings. Again, just my opinion.