I started buying Kikkoman's "whole bean" soy sauce (I don't remember what it's called in Japanese: maroyaka?), because I found a local Asian mart carried it, and it was reasonably priced. Seems you can find it on Amazon these days, even:

https://www.amazon.com/Kikkoman-Maroyaka-Sauce-33-8-Ounce-Pa...

Haven't compared it side-by-side with the normal stuff, but anecdotally it tasted a little more mellow to my palette, and I will probably continue using it moving forward when my 1L bottle runs out.