Do you mean BDA-1 and BDA-2? If so I would say BDA-2 because it has the latest AK 4399 chipset whereas the BDA 1 has the exact same older chipset as the BCD-1. There were several discussions about this when the BDA-1 and BCD-1 first came out and if I'm not mistaken the consensus was that there wasn't much to be gained by going outboard to the BDA-1.