nobody really knows what salt is better. Redsea and D&D (same as redsea pro + $20 because it has D&D on it) are supposedly manufactered through an inferior and cheaper (evaporation) processing technique compared to Kent and the salts where the high purity trace elements are blended by the manufacturer. I have used redsea many times with no major issues (there are better dissolving salts for sure).
Beyond that all you can compare are numbers that are useful to you. I have used reef salts with high calcium and magnesium and am back to instant ocean because I have come to prefer to start with seawater like parameters and manually dose to keep the levels where I want them. This offers much more precision for me than using reef salts high in calcium and magnesium. some people like high ca, mg numbers so they dont have to dose them. Some like the low ca/high alk salts because they prefer to keep that high. some look for salts high in specific elements like Potassium when using zeolite media which depletes potassium. then there are the bunch of trace elements we and even scientist have no idea what purpose they serve and if its beneficial to keep them below, at or above sea level. Just because somebody says X brand salt is great and made their life easier doesn't mean it wont suk for you. Both the salts you are looking at are typical "reef" salts with elevated trace elements. Oceanic is known to have really high calcium so if you arent heavily stocked with a bunch of hard corals its probably not a good choice. I've found seachem reef salt to be just as high.
