I meant to put for No.4 this one:
Most Helpful Girl
I think she looks pretty with all of them, but I especially like the pixie cut. She looks so elfin, which is a very beautiful look to me. The haircut also shows off her face best. I actually think she would look best with the pixie hair cut in the same color as the third picture. Blonde seems to suit her much better than that dark brown. The pixie cut + blonde combo would be perfect.