Brickburn's question is spot on: What is "quality"?
For some people only the trophy matters, others want an authentic hunting experience.
Hunting in Zambia, Tanzania , Mozambique and parts of Namibia is "proper" and what I would call "quality".
Buffalo are plentiful in SA, especially Limpopo province, but a lot of the hunting I wouldn't count as "quality" as the farms are frequently quite small and the majority of the animals are habituated . Some are also routinely fed in the dry winter months. The result is often a bit "canned".
The upside (unlike some of the places mentioned) is that you know the animals are there. It may take a day or two to find a good one but basically they cant get off the reserve, so its just a matter of finding the one you want - which you can sometimes do based on photos.
One also gets amazing animals in this region from time to time. Normally old bulls past their breeding age or bulls which are "problem animals" and so have to be culled. These can be really huge - as in tank sized.
Personally I'd rather hunt truly wild animals on big reserves, but it can be hard work, and in some places (eg Zim and Moz) you run a real risk of drawing a blank.
And then there's the question of accommodation. Some are happy with a simple tented camp or a "rondawel" with an outside cooking area, while for others only a five star lodge will do.
Thus the question remains - what is "quality"?