I'm really addicted to chocolate and ginger and on various trips to the UK have tried several commercial versions, with Walker's Ginger Royals being the brand of choice until now.
We just found Island Bakery Organics Chocolate Gingers, a company on Mull, which have blown the competition out of the water in my opinion: very very gingery, crunchy, and half dipped in good quality dark chocolate, with a candied ginger on top. All organic ingredients and no partially hydrogenated fats. I emailed the company and they said that they sell in the U.S. to Whole Foods. So if you too are a ginger addict, you might want to seek these out.