Thanks for the submission. I like overall form. Prefer the white background. Prefer Entry #3. I like the kanji characters. If it's a headband, maybe remove that. A black belt would be good. Arm positions are problematic. Too wild and uncontrolled. Something like these arms would be more controlled: http://whatthehealthmag.files.wordpress.com/2011/11/karate.gif
Entry #9 looks like a roundhouse kick, which is cool. Stance-wise, please bring the left are in a bit (slightly more bent), right arm a bit more forward. The right leg is ok since he seems to be reaching for the target and going high. However, the left leg would be more turned so that the knee is facing towards us, maybe a bit of a bent leg. Great shadowing.
Entry #11 looks like he's doing yoko geri kekome, which is also cool. Stance-wise, could you please bring the right arm in a bit (slightly more bent) and the left arm sloped a bit lower, left leg slightly bent and right leg a bit lower and body a bit straighter or slight lean back? The shadow is a bit off.
Please try one with just red and white for the logo border area (though keep the black belt and shadow on the guy).