Shae:
I am a new diver who is looking to continue diving recreationally, as well as making it a potential career option. I was wondering, what are the differences in certification organizations? I have my OW with NAUI and am looking into completing a DM program that is certified through PADI. Should I just stick with the one? I really enjoyed NAUI, but I am not finding as many courses offered in this format. If I am thinking about going through and getting my Instructor cert, is there any program that is better than any others? If I am thinking about teaching out of the country will that change anything?
At the instructor level there are differences between the agencies. These are mostly "philosopical" or ideology.
I will address only what I know about NAUI and PADI. Others can address the agency they are more familiar with.
NAUI has presents more skin diving skills in the OW class than PADI. NAUI has the students do recovery of unconscious divers both skin and scuba during the OW class. For me, that was important, while others don't feel that way.
As for teaching. NAUI allows much more freedom of presentation order and content than PADI. PADI does allow you to add mateial to the course but not with the flexibility that NAUI does. Again, for me, this was important, for others its not.
IMO, there is more academic material presented in NAUI courses than in PADI classes if you follow the curriculum. This was an important issue for me.
Both agencies are recognized worldwide.
I would recommend that you research all the agencies and talk to instructors from all of them that you can, so you can pick an agency that has a teaching philosophy that matches your philosophy.
Bear in mind also that all agencies have excellent, good, mediocre and bad instructors. The key is to put yourself in that first category regardless of the agency you choose.