Personally speaking, the one in the left is the one that caughts my attention in terms of composition and character arrangement, however, when it comes to the coloring, the right one is the one that stands out to me more.
I believe you could enhance the left one by incorporating a similar background like the right one, probably use another source of shadow to create a gradient, and another one for lights. Since it seems to be shiny, maybe some lense effect besides providing a solid shading similar to the one in the right. Which also provides to why it stands out more than the left one, as in terms of coloring goes to a more "flat" render.
