I voted for #4 simply because I think it would be rather easy to fix up for a fun signature. The harsh lighting would make it easier to do something simple and quick while still showing your eyes.
#1 - I simply don't think the lighting or angle are good in this one...your eyes are gorgeous, but I think its mainly the lighting.
#2 - I'd vote for this one too - same comments on the harsh lighting, but I think your eyes came out better on #4 (but I will admit I like the angle you have on this one better, with the side showing the curve of your face)
#3 - Your face was smooth and your "expression" is kind of sly, but your eyes didn't come out very well in this one
#4 - I already said why I voted for four
#5 - I didn't vote for 5 simply because while your eyes are gorgeous and come out brilliantly, the rest of your face was rather pixelated.
I think if you could create the angle from 2 with the gorgeous and vivid coloring of 5, it would be perfect. I love the fact that you can see the ring around your eyes on 5. Unfortunately, I think that's because the quality was not quite as good as the others. I'm not quite sure. Futhermore, it looks like you took the pictures using a webcam. I say this because I'm not sure if the light in your eyes (it looks like the reflection of a laptop screen) works to your advantage or if its a distraction. I think it takes away from the color in your eyes at any rate.
My humble opinion...