I think #1 is the strongest for a couple of reasons. First, the b&w. Shots like this are ALWAYS more powerful in b&w IMO. Also, the model is looking at the camera. While that's not always necessary, I think with this series it seems to add something. #3 would blow the others away if she was looking back toward the camera, her head tilted back just a bit more. With #3 the power is in that odd jumbled juxtaposition of her legs.
Also, a nitpick, but I'm not overly keen on the selective softening on the 2nd two. If it was less of it, it'd be okay, but like on #3, look at the model's left foot. My eye is naturally pulled away from her foot and onto that area where the detail suddenly blurs away.