All rough draft, I can't tell if I'm making the eyes grey or light blue, and for the face it's pure black on white, no shading or anything.
Some are just plain stupid, but add to the general idea. My vote is bottom left.

More round is kinda hard, the mouth is 2, 3 or 4 pixels high, adding a pixel to the side looks really weird, look at number 2.

NC in the US of America

I like 6 and 12 and 13 the best.