What cookie sells the most?

Could you please elaborate on the context of this question? Are we discussing a bakery, a supermarket, or perhaps an online store that specializes in cookies? Additionally, is there a specific brand, flavor, or type of cookie that you're interested in? Without further information, it's difficult to provide a definitive answer to "What cookie sells the most?" as it can vary greatly depending on location, time of year, and consumer preferences. However, in general, classic flavors such as chocolate chip, oatmeal raisin, and sugar cookies tend to be popular sellers across various markets.