Prefold Cloth Diapers

For those that cloth diaper, when using prefolds or flats, is it important to still have hemp or bamboo like most people say for all other cloth diapers? I have seen that people like to use Green Mountain Cloth-eez prefolds, but there is chlorine-free white, chlorine-free unbleached, and organic cotton. How do I decide which ones to use? Is organic just as good as using hemp or bamboo? I also found Diaper Rite Bamboo prefolds, which seem to have great reviews as well.