I go through a lot of salt with regular partial WCs on a couple big systems, so "I" go for the "cheapest"...whatevers on sale between IO...Reef Crystals and Tropic Marin...
The big warehouse outlet up by me often runs these "inhouse" sales between the brands, so I try to get the Reef Crystals or Tropic when on sale...but usually the IO is the low dog...
Seems like most any brand you choose will have "some" inconsistancies in the basic formula from time to time (due to settling/packaging) but as long as they're not "drastic" (killer ALK, or NO calcium) it really doesn't matter ..My corals don't live in my mixing tank, they thrive in my Main tank..that's where I do my testing and adjusting...