I read an article when i first started, that basically said for general cost, that instant ocean reef crystals was the best choice when you factor in how much supplements cost and how long they last. The article stated that red sea was marginally better, but the premium cost does not outweigh it at a rate of per gallon it makes.
That being said, i chose IORC, but i am going to get a container of red sea, just to see if there is any difference, as soon as I get down to about the "20 gallons left" line of my IORC bucket.