2, 3, 4, and 5 have blown out highlights, which are distracting. Watch out for cutting off the tops of heads, or having the hair bumping the top of the image. On your last picture, the necklace is more in focus than the eyes. How is your camera focus set up? Center, honeycomb, etc.
I absolutely love the first one. The composition and focus, as well as the lighting are perfect!