The reason I chose this as my best is because I feel that the strong horizontal line is strengthen by the verticals behind it. Also the drops of water are sharp and strong along with the leaf they sit upon. As for Depth of View, it is the range from near to far(to the camera) of focus; therefore to get better control of DoF you need your aperture, focus length, space and sensor size.
Lovely. This photo is a good example of shallow depth of field. The leaf with the water droplets is very sharp while the leaves behind it are a bit out of focus.