I've used Oceanic, Reef Crystals, SeaChem, Red Sea, Red Sea Coral Pro, Instant Ocean, and a few other brands that either aren't carried locally or are discontinued now.
Instant Ocean is a great salt...for the price you really can't beat it. You can use IO even if you have a reef...but once you get more demanding corals, you may have to supplement more (alk, ca, mag). I used it until it was just more affordable to get a better salt rather than using IO and dosing a lot more to maintain parameters.
I currently use SeaChem. I've had amazing results with it...much better than the results I had with Red Sea Coral Pro. Occasionally I'll get a bucket a bit low in magnesium, but that's about it.
Aquatic Mouse - be careful dosing iodine. It's very complicated to test for...and you shouldn't just dose things if you can't test for them. Iodine if dosed too much can cause shrimps, crabs, etc to molt at an unnatural rate...and has been shown to cause an even shortened life than normal in captivity.
Also, Purple-up is just really expensive baking soda, epsom salts, and calcium...and a few trace things. At this point in your tank, you shouldn't have much really sucking the alk, ca, mag levels down enough to need to dose with Purple-Up with frequent water changes. Of course, it seems to work b/c your tank is naturally growing coralline based on what is in the salt mix already. If you start having low levels of ca, mag, & alk, you can either switch to a salt with elevated levels of those to begin with...or buy chemicals in bulk to dose. Much more affordable that way...and you know better what is going into your tank!