As someone who has both NAUI and PADI certs I can say one thing for sure. PADI is more expensive. PADI is just one more dollar for something else, you need x, y or z. As far as I am concerned when I take a course for x dollars it should have all the material with it. I can understand a collage course for credit, but sport diving is not the same. In the NAUI courses I have taken, the binder had everything you need in it and it came with the course. One payment for the whole nine yards not surprises. What I hate is the 25 for this book, the 32 for that book, the 16.50 for this CD and 45.50 for the DVD etc etc etc.
Maybe it’s just me but it seems like an ongoing money thing with PADI, they always want more. As far as the agencies are concerned, they are about the same. They do teach different things at different times, like NAUI stresses first aid in the OW course and more so in the AOW level right off the bat. NAUI has allot of emphasis on first aid at the AOW level much more so then PADI. PADI does not get into it deep until Rescue diver level. Also for NAUI I needed a current CPR and First aid course for my AOW. Seems like first aid/CPR should be in all AOW level courses for all agencies. Recue diver should be on rescue techniques and in the water training, not the book work, as that should already be done long before that point.
Just my nickel worth, and I KNOW someone will take offence to my remarks!!!