Marukin Shiboritate Shoyu (17 oz, $6)
Ohsawa Organic Nama Shoyu (10 oz, $10)
I got both at Tokyo Fish Market in Berkeley. The Marukin has been my standard gourmet soy sauce for a few years now; I discovered it at a food fair. The Ohsawa was publicized by Cooks Illustrated when it won a taste test, and I just found it at the store. I was quite curious, so I tried both and compared.
Oddly, even though the Marukin was much darker in color, the flavors were close enough to call it a draw. Both tasted way better than standard brands, e.g. Kikkoman. Also, these are only for use as a dip or drizzle. If you are going to cook with it, use a cheaper brand, as they all tend to taste alike once you expose them to heat. The only problem is that they are only available at a well-stocked Japanese grocery store or on the web.