Coming at it from a geographical/historical perspective would seem to make more sense. Let's try.
[For convenience I use OTL names. I'm ignoring Madagascar, Sao Tome & Principe, et cetera because I feel like it.]
The Ottomans got an impressive swathe of central Africa despite lacking Egypt, but lost it all because of the awkwardness of going through Libya. Egypt meanwhile, extended itself south to sweep around the edges of Ethiopia. If we assume that Egypt is never separated from the Ottomans, or is reabsorbed in the early 19th century, we can reasonably expect everything from Tunis to Central Africa to Eritrea under their rule. If the empire lasts to the modern day and allows local autonomy, so could their African holdings. I'll come back to Ethiopia and Nigeria, both of which are at the edges of their reach.
Zanzibar originally held a huge swathe of Africa extending from central Somalia to northern Mozambique and inland to the eastern parts of modern DRoCongo and Uganda. They were gradually strengthening their hold into real political rule under British protection before the Scramble. Assuming the British aren't in Egypt, they'll remain in their influential position over Zanzibar and encourage it to solidify into a proper state between Ethiopia and Mozambique. I'll come back to Ethiopia and Mozambique - it couldn't really handle them.
South Africa clearly had the potential to incorporate more of the area around it. It mainly needed a more diffuse/federal structure so it could incorporate other white-ruled states (who'd want autonomy) and black-ruled states (who would not be welcome voting in such a nation for a long time). Say a federal arrangement is proposed among the white-ruled Namibia, Cape, Natal, Transvaal, and Orange, with Botswana, Lesotho, and Swaziland as incorporated "princely states" / "apartheid republics." This could easily expand over time to include white Zimbabwe and black Zambia. Portugal's colonies can be divided after a bankruptcy at some point, adding Mozambique to the bargain. I'll come back to Angola, as any division of Portugal's colonies would see Angola and Mozambique going to different powers.
The Congo is the other big region we can easily tie together. The two Congos - RoC and DRoC - are naturally a single unit and could survive as one nation at least to the extent that the DRoC does in OTL, more if we're careful. A single power - France, Germany, or Portugal - could potentially have built a strong-for-Africa state at the center of the continent. It would include both Congos and the southern portion of the CAR. If a power or the powers were trying to build a weighty state for some reason, Gabon and Equatorial Guinea could be incorporated pretty easily. They might not even leave, either! Again, Angola might be a bit much. I'll come back to it.
Okay. That's the four easy ones. Between the Porte, Zanzibar, South Africa, and Congo you have most of Africa done already. We're left with Ethiopia, Angola, North Africa, and West Africa - the region least compatible with running states in the entire world (if you except the Poles).
We have only three more nations to use.
