As with most debated topics in this hobby, it depends. If you are interested in a deep sand bed to keep your nitrates low, use the fine (.05-1.0 mm) aragonite. If you want a very shallow sand that you will vaccume to keep clean, then maybe something more coarse. It also depends on what kind of sand stirers (if any) you want. A lot of it is also pure opinion as to what you think looks best. IMO I like the fine (<1.0mm) white aragonite for it's look and function. I also have a goby/pistol shrimp which seem to perfer to burrow in this stuff. Oh, and whatever you choose, I would never WASTE my money on "live" sand. There is nothing alive in there other then some bacteria which will colonize your sand within a matter of days anyway if you just throw some live rock in there, use some of an established tank's water, or heck just toss a small piece of your cocktail shrimp.