Sok - I don't really get what you mean by variations here, or ehat's going on with all the forms. perhaps you could explain a bit what we're looking at?
ben - i don't think dr manhattan, death, and a recolor are really going to register high for creativity or usability, and you've gone with your bizarre habit of changing (completely) the material presented. Sure, it's a nice head, but it's not exactly what sokota is doing, at all. Part of offering good advice is stepping outside your own tastes and desires and trying to meet the artist with insight that is unique and distanced, but at the same time relevant and accessible for the purposes of this piece. You do this in almost every thread, it's been commented on, and perhaps I am talking to a wall, but I've always found it distracting.
That said, Sok, ben does use a better implementation of value in his example and i would encourage you to look into a similar idea of using wider values to sculpt forms, or post these on the real background so that we can see how they work - against this gray they bleed out and lose all form, but against a dark background, they would hold up fine.