PADI, while a great association to be certified with, has earned a certain measure of scorn in the diving community, the foremost being the aforementioned "Put Another Dollar In" gag. A great many also feel that PADI is the way to go for amateurs and tourists, but more serious divers might be better off with another certification. Having been certified with both PADI and NAUI, I can safely say that the NAUI open-water course was more stringent and covered more ground (or water, yuk yuk) than the PADI equivalent. I also tend to like NAUI dive tables over PADI, for some reason.