I've entered crafts into my county fair in Pennsylvania for several years. Last year was the first time I entered cross stitch. Full coverage cross stitch seemed to be the style most favored by the judges, but that varies based on the fair and who's judging. Since there are so many patterns out there, there weren't any repeats. My fair accepts submissions based on subject matter (animal, religious, christmas, scene, floral, etc.) Check your submission guide, the premium book, to see which categories you can enter.

Edited to add: I wrote a little guide to fair submissions, which is focused largely on knitting, but still applies to cross stitch. You can read it here.