Ooh, this is an impossible question. There are so many good options and it depends on your style. My calves are 13" and I love my Frye Riders. They have a western flair and I wear them with leggings, boots, skirts and dresses. All of the other suggestions are fab, too.
If you like lace-up options, the Melissa Lace style is fun and can be fitted to a very small calf depending on shoe size. I bought a pair yesterday that I need to post pics of.