Gekkeikan is the largest brewer of sake in the world, and although I can't say from experience, it should be a safe bet. If it doesn't meet your taste when chilled, drinking it warm (or hot) will help to mask the roughness somewhat. You seem to have figured this out already, however. This is actually the reason sake is traditionally served warm; in the past, it was not very refined, and this helped smooth out the taste. However, sake is much more refined today, and generally should not need to be served warm (unless you are buying the cheap stuff). Also, sake is not aged, and what I have read says that it is generally consumed within a year of brewing, which may be why there is no "best before" date on the label. I'm not sure what happens if it is allowed to sit. Finally, don't let sake sit too long after you have opened it, because it does not use preservatives and will go bad.
If someone can vouch for Gekkeikan's quality (I am no connoisseur when it comes to sake), it may just be that you just don't like the stuff. Nothing wrong with that, though.
