As a surgeon, i would advise you that you get what you pay for. Personally, the family and i are on oxygen premium plus. I think that all the Fedhealth plans are good. Discovery Classic is also worthwhile.
There are essentially two levels of payment. What is called the "medical aid rate" or 100% cover. This covers the MINIMUM amount that any doctor would charge. However, doctors can charge up to three times this, the so-called MASA or PRIVATE rate. Generally your specialists in the more upmarket hospitals will charge the private rate. Very few gp's and even fewer specialists will charge medical aid rates, which are really rather pathetic. Most guys charge somewhere in-between e.g. i charge 200%.
Most medical aids will pay your hospital bill in full, what they don't cover in full is the cost of the doctors whilst you're in hospital. Also, some may cover your out of hospital expenses in full or at least to a greater or lesser degree -this is usually the essential difference between all the plans.
If you're relatively young and healthy, go for a plan that gives you 300% cover in hospital and modest cover out of hospital.
Bonitas can be problematic and you will probably have to pay out of pocket for most things. However, they have relatively good out of hospital cover.