sand is suppose to be better because it lets the root grow better. But IMO, as long as the plant is planted its all good. I dont do the LB per G rule. i use about 20-30lb for a 60g. More sand more bacteria (good and bad) to be collected.
I think i'm actually going to go with a bag of play sand and clean it up really good before i put it in. I would rather clean it for a long time for a fifty pound bag at $2 then pay over $30 for the black sand i liked that there isn't even enough of..