I grew up using Kikkoman soy sauce and never really thought very seriously about soy sauce at all. Kikkoman seemed like a good all-purpose sauce and I used it whenever a recipe called for soy sauce regardless of what cuisine it was. But lately, I've been thinking a lot about soy sauce. Initially, I was mostly concerned with finding a sauce that didn't have sodium benzoate, a nasty preservative that's in practically everything, including liquid vitamins. But now, I'm concerned about taste. I had no idea how different soy sauces can be, from Kikkoman to Yama to Marukin.
Marukin is the one I've been using most. According to the label, it has no preservatives at all and must be kept in the fridge. It's much more salty and intense than Kikkoman so a little goes a long way.
The second soy sauce I now have is a brand called 수복표 국간장. Yup, the name of the brand is only in Korean. Strange for a soy sauce made in Los Angeles. In English, the brand name is Soo Bok. Like Marukin, there are no preservatives (again, I have to trust the label). But unlike Marukin, there's no wheat. That's really the difference between Japanese and Korean soy sauces, Japanese being a combo of soy beans and wheat, Korean being pure soy beans. 수복표 국간장 is absolutely lovely. The sauce is light and clear with a delicate, though very salty, taste. Really recommend it for all Korean food.
Of course, if you're cooking Chinese food, you really should use a Chinese soy sauce, but I haven't found a really good brand yet. Pearl River Bridge is the brand most available in the U.S., but I've never been terribly impressed by Pearl. Any recommendations out there?