The best of the not-big selection at my local grocery store -
If money, time, and travel were no object, I'd go
first - to San Francisco, to a little chocolate bar store in the downtown area and work my way through trying all their choices..
second, to Gran Caffe Orientale in Parma, Italy, where, besides fantastic coffee, they had individual chocolates in glass cases, every one I tried to die for. They didn't have chocolate bars, that I noticed, or maybe they did, but the candies were the best I've tried.