LA County
NAUI
PADI
SSI
TDI
GUE
If you can, get LA County cert, but be prepared to work for it
It is more the instructor than the agency, that said the majority of dive shops are PADI and alot of shops push the two weekend certs. The instructors are told that if they follow the program to the letter and something happens to a student, the agency is on trial, not the instructor, but if they add anything not in the book.... so you get a lot of text book instructions...
NAUI gives their instructors more freedom. My NAUI instructor made up his own tests, when we corrected the tests many of us had different answers. We were asked why we chose a certain answer and if our logic was sound and their was obviously thinking behind our choice, we were right.
TDI has a sister company that does open water certs, but TDI is based more on continuing education, nitrox, advanced nitrox, deco, trimix, blah blah blah. Major instrucot freedom, crappy books!
Dont know much about SSI, one shop out here that is SSI and I would never take a class there or buy anything.... owner and employees give off very bad taste. Not thrilled when you get special cards after x amount of dives though. I know of people with literally hundreds of dives that I will never dive with again!
GUE Global Underwater Explorers.... whew where to begin? alot of online debate here... milataristic/no nonsense hardcore training. You take their first class Fundimentals of Diving knowing you are not going to pass. You will develope "spot on" bouancy control, situational awareness, propulsion techniques (never flutter kick) including swimming backwares and spinning in circles with out ever using your hands. After you get certified and get comfy in the water I highly recomend this class. The downfall, it may be hard to find an instructor, they only allow certain types of gear(backplate with wings, short stiff bladed fins like jets, 7 foot primary regualtor with backup bungied as a necklace) you see how effortless you instructor moves in the water with such a high level of control, you spend a lot of time in the water practicing your skills.