Both covers are attractive. The little boy in B is compelling, but the background is too dark, and he's too small. The idea is right but it gets lost. My eyes immediately went to A because of the yellow and the brightness of that cover. It's thoughtful but uplifting at the same time. If these are your final choices, I would go with A.
I liked both of them. I thought A had broader appeal but the photo on B was very compelling. I'd pick up either of them and have a second look. Best wishes.