I like the BMTron one, everything else has a sharp outline with no stroke that makes the picture ugly
As for the text effects/pattern overlay, they are good but needs a soft light or increase the transparency by around 15%, dont forget about the shadow about size 5px opacity 75% multiply.
I'm going to have to disagree with Rey, because although I like the effects you made on the BMTRON one I think the difference in color and font make it look weird. Also, the shadow is a bit to far away from the actual text for my taste. (especially behind the ''n'')
The Chai ones look very nice (apart from the animated one) because somehow the patterns and effects inside really fit the font you used.
All this siggies are specifically crafted for darker background.