I use instant ocean on my FO tanks and kent marine on my reef. I think they work very well, and i have used Oceanic before, which is a very good salt mix as well.
red sea works ok, i usually buy my water premixed i think they all use IO (cheaper)
but when i'm filling the 1 gal or a 2 gall for like a nano macroalgea tank or something i use the red sea cause they com in 5 gallon bags