It just reminds me of skirmishes here at my college between my fraternity and the others. It is impossible to say which one is best and why, with a definitive answer. I am certified through PADI, but I am not going to be so bold as to say, "It is the best agency to get certified by." It all boils down to the person absorbing the training, and applying it. Some people could get 3 years instruction from a Navy Seal, and still get shown up by a person on their first OW dive. I will say this, I feel comfortable with the instruction I received from PADI that it makes me a competent and safe diver. I’m sure most reasonable people who are of average intelligence, feel the same way about their instruction(from any agency), and feel confident in diving. That is what it all boils down to.