#16 - at first I didn't catch the implied helmet. I like the concept, can you tweek it a bit more so it is more recognizable as a helmet? And do something else with the fonts.
#18 Love the action on this one. It implies almost a high kick to the face! :) Can you try some different fonts and typography placement? Also let's see what else looks good behind the shirt instead of the star burst, maybe a circle, or some slanted oval?
Thanks for your detail feedback. #16 is my favorit since the shirt hide cleverly. Potentially make people say wow! and remember for long lasting. Here #34 is it's update work.