In my opinion none of those signatures reaches to a level that could be called a signature except for Risquette.
Feel free to hate me if you think I'm wrong, but do browse on other GFX forums and see what other GFX artist would say.
So I shall place my vote on Risquette, since that actually reaches the basic skills needed in order to make a decent signature. (But still lack depth,lightning)
I understand that you're not trying to be rude but pretty much the sole purpose of competitions like this is for people to improve so rather than insulting everyone's work maybe you should...not.
On a lighter note, having said what you said, if you don't enter and win the next SotW, you best eat your own face. And I'm going to enter c:
EDIT: Btw a signature doesn't have to have good lighting (and other necessary parts of a beautiful piece of art) if they're not trying
to make it realistic. That stuff's only really necessary if you're doing photomanipulation or trying to prove you're good to a forum (like most do.)