For me, both of S Builder Co-op and PSA to go are better. But if you want to have sure PSA into your downline, you can choose PSA to go, of coarse more expensive than s builder Co-op.. You can also try other ECAs the selling PSAs, cheaper but i dont know if the quality is good.. For those who dont have time to invite downlines and advertise your sfi business, better buy or subscribe Sbuilder Co-op or PSA to go to build your successful SFI business.