Black sand does look better IMO. For me the deciding factor would be what bottom dwellers I keep in the tank.
sevank21 I hear yah bare bottom is so convinient I always suggest to paint your tank bottom black before set up just in case you change your mind about substrate and want to go that way, but yes tractor supply is best for black sand but lesllies PFS looks nice or if tank is still dry and want to go dark on bottom some cool black marble tile with green lightning streeks in it siliconed down would be nice post pics when filled...