Actually there is no absolute answer which method is good, for my first tank, i used bare bottom but I just don't like that a reef tank without sand bed. Recently I've set up a new tank and I decided to use sand bed, it look more natural to me, both methods so far do not affect water parameter, i still managed to keep No3 and Po4 at 0. You can try black sand and it will give you a contrast effect for everything you put in the tank.