I believe this photo is the best of the selects, for a number of reasons; the white balance is good, the crop and the relationship to the subject.
The first thing that stood out to my about this picture, is the white balance. The background isn't blown out and has great detail. The subject's skin tone is also normal. The shadows are soft and not distracting too.
I like the crop in this image too. Some of the other photos Were cropped longer down and showed more of the table but I believe it wasn't as strong as this image. I think the tighter crop at the bottom allows for the viewer to focus on the artwork hes creating. This also helps with the rule of thirds and put the horizon lower rather than centered like some of the others.
This photo is more intense than the other ones, in my opinion. The subject is centered, and although sometimes I try to avoid putting my subject in the center, I think it works with the expression the subject is giving. There's a connection between the viewer and the subject in this image because the first thing my eyes look at are the subjects eyes.
A lot of the images were extremely similar but this photo stood out to me for the reasons listed above. I think this is the best portrait from the group.