> I am hoping a group of mostly stable countries band together and make it happen first. My founders list would be Namibia, Botswana, Angola, Zambia, Malawi, Mozambique, Tanzania, and Kenya. A nice list stretching from the Atlantic to the Indian Ocean. These are moderate names, not often in the news and stable for the most part. If South Africa would join that would be a big win... but I am hoping one of the smaller countries takes leadership initially.
I'm guessing you're pulling this list mostly on the basis on geographical proximity and "these haven't been in the news", as opposed to examples of African success. Angola definitely shouldn't be on that list (it's basically a kleptocratic petrostate à la Algeria), and Kenya is eyebrow-worthy.
In general, the best-run states of Africa are geographically dispersed. The island nations of Cape Verde, Seychelles, and Mauritius; Botswana and Namibia; Tunisia and Morocco; maybe Gabon and Ghana will generally top all of the various lists of economically successful, well-run, well-developed, democratically free. Rwanda would be on the list were it not for being fairly autocratic--most notably, it's a very rare example of an autocratic country that's fairly free of corruption. South Africa is notable for pretty much backsliding on all of these metrics, despite starting from a relatively high position.
The AU is split up into multiple blocs, each supposedly working towards eventual unity. The East African bloc (Kenya, Tanzania, Rwanda, Burundi, and Uganda) has generally been the furthest along, and the South African bloc (in particular, Namibia, Botswana, South Africa, Swaziland, and Lesotho) the second. It should be noted, though, that actual adherence to the currently-enacted treaties can be rather thin on the ground.