Ok, I know this will probably seem mean, but I'm trying not to be =\
Ok, so there are basically 2 types of sigs, there are many way to categorize it, this is one way... I'll show you the type of sigs I make and compare it to yours...
Mine:
In this type of sig, you focus on artisitc elements, such as depth, flow, focals, lighting, many things such as those. If you look at my sig, where do your eyes lock onto? House, right? Since thats my focal, thats what I want, for the eyes to go to him. I created a light source... the "sun" on the top right of his face, see how the other side of his face lays in the shadow? I have depth, it looks like things are farther away or closer. Many elements come togehter in one.
Yours:
Color flows nicely, really nice design, you know what you are doing, nice effects BUT, you are missing elements such ad depth or basically, the sense of realism, although not everything needs to be real, such as an abstract sig, yet real properties apply. talking about ur other sigs, dont let text be the main part unless the text is special, you usually have many focals, your eyes don't know where to look at.
Not saying ones better than the other, U kno alot more about how to create things in photoshop than I do, but I just wanted to show you the other type, open up your eyes a little, just to show you whats out there
Keep on siggin'