Scott_R - 3/03/2017 9:56 PM
Like others have said, the instructor is important. It is an incredibly difficult task to evaluate this without taking classes from both of them. One consideration might be finding out what specialties each instructor is authorized to teach and find out who has more that match your interests. This may be something to consider even between instructors from the same agency.
Some agencies give instructors a lot of freedom to do their own thing and this can be a good thing if you have a great instructor or a bad thing if you have a not so great instructor. I don’t know where SDI falls in this regard but I can tell you PADI has a fairly regimented program. That means all instructors need to generally follow the same program and teach the same material to the same standard. That standard has recently been increased to teaching skills neutrally buoyant rather than kneeling on the bottom. PADI standards translate into a fairly consistent result as opposed to wide variation you can find when instructors are given more freedom. It is obviously a pretty good system because for the 19th consecutive year, PADI has been awarded the prestigious TAUCHEN Award for Best Diver Training Organization.

I can’t speak to the prerequisites for SDI but AOW for PADI is intended to follow OW and gives divers a lot of choice in the type of diving they want to do. PADI is super flexible on AOW. You choose 5 specialties of your choice to try out. If you run out of time or maybe you only have interest in 3 areas, you can stop at 3 dives and earn the adventure diver cert. You can go back any time and finish up. Some people will say this doesn’t make you what they consider an "advanced" diver. You will be advanced past open water and that is the point. PADI allows you to baby step your way through OW & AOW if you want or need to.

AOW is not a scam. It gets you additional diving experience under the supervision of an instructor. It gives you exposure to different types of diving you did not experience in your open water course and introduces task loading.

I am not saying SDI is bad and I swear I didn’t drink the PADI kool-aid. I just know the PADI program and I think it is tough to beat.