There are a lot of quality operators in both RSA and Namibia. Jon Olefse safaris in Namibia is a top operation. Madabula in RSA is worth considering.
But before you try to focus on a particular PH, you need to decide what you want from this trip. A luxury resort with french chefs and some absolutely stunning accommodations? - Consider Mkuze in RSA.
A ranch style hunt fairly similar to Montana, but with mountains teeming with African game - consider the east cape in the Winterberg mountains.
A traditional "thornbush" safari somewhat akin to Texas hunting, but many tourist attractions somewhat close by (like Kruger) - than think about the Limpopo province.
A camp with some American influence and truly remote country, with exceptional variety of animals, including 4 of the big 5 - then check out Olefse.
These are all great trips. And just simple one sentence descriptions of each, but they all have so much more to offer. You may not even appreciate the variety of options available in southern Africa, but it is a lot like trying to compare hunts in North America. A whitetail hunt on the east coast is nothing like an elk hunt in the Rockies or a Coues hunt in AZ. They are all great, but it helps if you know what you are looking for to make sure your expectations are met.