I've used a few of them and found Dietmar and Rafaella Posch to be better for low client to DM ratio. I believe their website is still down but the email is info@gentle-blue.com He is also apparently the Seacam dealer for South Africa.
Dietmar is based in Umkomaas which is sort of the dive central of KZN.
I would also suggest you stay at the Agulhas House where Dietmar is based. It's very nicely decorated,secure, quiet, convenient and has wifi internet. The owner Mickey is a former owner of a dive ops and very dive friendly too. The only thing is food isn't the best thing in Umkomaas. LalaMantzi has decent food. Taste is now not so good and Sebatian's is just typical greasy food.
Scottsburgh has better restaurants but busier and you'll need a car to get around.
Aliwal is known for the tiger and raggie (C. Taurus) shark dives. They do chum and some operators feed them so I don't go anymore. The behavior has been altered completely. There are also plenty of Black tip sharks around (C. Limbatus).
You may also want to consider Sodwana Bay. The diving is better for fish other than sharks and Nov is the beginning of whaleshark season. It is more rugged as a place but the beaches are wonderfully not as crowded and the surf entry makes it an exhilarating ride. I use Gypsea Diver's Rob Bester gypsea@saol.com
as many of the others are very much cattle car operations. Book yourself into the Sodwana lodge.