Its big enough where it doesn't blow around a tank that has a good amount of flow too easily and small enough that sand sifters and fish clean the sand can do their thing still.
I prefer medium to coarse light colored sands, both of my reef tank builds have had CaribSea Arag-Alive Fiji Pink sand and I have had a good experience overall with it. It's a bit dusty initially so a rinse or two would probably be good for it.