DC's Signature could be better if the Color of his Background would blend along with the Rendered Image. Its not only Copy, and Paste. He focuses much more on the Background rather than on the Render, which is cool.
But, adding some effects to the rendered Image will not harm him. Maybe a little Pen Tool, and C4D will make the Signature much better, and focus more on the Face at least.
I like B.D's Signature here the most, but the Background turned her down. ReWritable's Signature is awesome. StampCoin pretty much over done the Spiral Brushes.