Short answer - White
Long answer -
I have had the white sand for two years, previously had crushed quartz and it was stunning, but got green algae and sun and chlorine bleached and boiled and scrubbed with salt, nothing kept it away. Also had natural gravel.
After going with the original sand, the CaribSea Super Naturals Moonlight sand, every one always comments on how amazing it looks. Not had any algae issues as of this writing. Fine grains just floats too much and eats up impellers. Although is easy to clean, just vacuum.
Bought the Black Petco sand and it looks great in the Edge aquarium and it looks too dark for my liking in my 32 half hex, also have dark root rock/ back ground just too dark for me. Doesn't float into filter but is a little funny occasionally a small bunch of sand will float until you poke it with your finger then sinks. Very light and the Cories love it.
A friend of mine has the tannish natural sand and it looks good especially with plants very natural.
Sorry this is such a long answer, but I like the white the best. I think it takes the look up a notch toward elegant. I was originally going to go with black.
The garnet sand can be in several colors depending on where it is mined. Some tending toward tan and black but there is multi color effect with golds, tan, red, black or - rosey purple or - purple, grey, black, white. Pretty neat combinations.
I will vacuum the sand again, and scoop out some of the little black specs of sand when I have more time. lol should get the most of it.