I tried the following salt; when I first set up, I started with Instant Ocean, which I didn't have any complaints with. My water parameters stayed good and everything was thriving.
I heard that Oceanic was better, so I tried a bag of that, the only difference I noticed with that (besides being more expensive) was the calcium levels always were 500 (maybe more) per salifert test kit.
From there I was going to switch back to Instant Ocean, but decided to give Red Sea a try (which I am using now). My calcium levels have dropped to 380, my corals went into distress, I am adding a calcium supplement to get the levels back up. I am going out today to get bag of Instant Ocean. Now that I've tried a few, I believe I will stick with that. The price isn't bad, my tank occupants thrived well on it.. I guess what they say is true, if it ain't broke. Don't fix it...