Salt debates come up every few months. To be honest, nearly all salts on the market today are "good". There isn't any truly bad salts out there. They all have a certain level of elements they shoot for. Low alk, high, alk, etc. find a salt that meets the parameters of your tank and you are good to go. Some of the cheaper salts tend to be more inconsistent from batch to batch but even high end salts can vary.
One thing to note is that some brands use a clay binder in their mix. This will cause the water to appear cloudy after mixing and will also dirty your mixing container much faster. The residue you see inside the mixing container. It's not bad, it can just make your tank cloudy for a day or two after a water change. I personally use Tropic Marin Pro. Their Alk, Cal, and Mag matches my tank perfectly, no clay binder so it mixes clean, clear, and fast. They are also extremely consistent in the levels of their elements. I used to test my new water before putting it in my tank. After months of the same readings I quit. Hope this helps some in choosing a salt brand.