I really like #2 & 3. I'm not sure about one but thats only because the little boy is too dark but I still like #1 because of the way that the tree is dark and then you have the white rocks. Well anyways, they are all nice shots eitherway.
I prefer the first one because of the physical contrast between nature and the child. The tree and leaves in autumn, the hardness of the rocks and the playfullness of the child. Also the contrast of the child agains the bright rocks in the background results to a focus of the behaviour of the child itself instead of the child as an individual.
I like these images. I think it might help #1 to crop in slightly from the right, to put the tree trunk off center. As it is now, the tree trunk pulls your eye away from the boy, and you don't have as much emphasis on the wonderful positive/negative space around the shape of the boy.