Some that or great, some that are pretty poor.
Lots of your sigs have way too much in them; they contain more than one graphics, or set of graphics. Making them ugly.
You use the lightning effect WAY too much.
Your borders are not the best; maybe stick to a 1px black stroke?
Text and brushing seems to be your weakest point here. Try blending in the text with effects; smudging, blurring, sharpening, contrasting colours, etc etc.
As for brushing... keep to one set of brushes AT ALL TIMES when doing a sig. If you interchange then it looks messy and poor.
Trust me, you can tell.
The best?
It would be the frog one if you had cleared some of the light off the BG behind the frog.
So it would have to be your last one.