A long time ago I used Tropic Marin, which was by far the best salt around. I even used it in my fish only tanks and you could really see the difference. Over the last ten years or so I started to use IO in my fish only tanks, as the salt got somewhat better and Tropic Marin also got very expensive. I continue to use Tropic Marin in my reef tank but I had issues with Phosphates, so I switch to Coral Life and then IO, where I had to add Alk and Cal to get it up to the levels that I wanted. I moved to ESV for a number of years but I just didn't see any different results, and for the additional price it wasn't worth it. Recently I think I got 2 of the bad batches that they sent out and develop a lot of hair algae from it. I switch over to Red Sea Pro and the results have really been amazing. The hair algae went away, corals were fully open, a lot of growth, and I was actually able to do less water changes.
All of these salts do go on sell from time to time, so you can always find what you're looking for at a cheaper price. It's also good to stock up on it when you do find it on sale. I probably have enough salt in my closet to salt the neighborhood the next time it snows.