#01 : too much space above the head. Showing full body rather than a lot of sky would have worked a lot better. In order to achieve good full body shot, kneeling is often a good start.
#02 : needs a little straightening. Otherwise the composition works well.
#03 : The sky being all white, it's an empty space. Also, the sides do not bring anything to the picture, so cropping a lot more tightly around the cosplayer would make it a lot more interesting, and make us wonder whether the snow was actually falling
Hope this helps !