The winner will be an option for the Moto 360 when it goes on sale. As mentioned in this AndroidPolice article, you vote by going to the Google+ page in the link and giving a +1 to your choice(s). You can vote as many times as the number of Google accounts you have.

I'm happy to see this one in the lead, since it was my favorite of the 10, but if you disagree, then give whichever one you prefer your vote. Voting is supposed to run through June 24.