Ooh, threads on this subject are always so interesting, I never go away without having learned something.
The amount of these that would actually be viable would be pretty modest. The Angolan coast is about as far north as European settlement can safely extend before the advent of quinine and other medicinal advances historically made around the time of the OTL Scramble for Africa (a reason for its occurrence really), and even with malaria brought under control, things like the tsetse fly and associated maladies (namely the sleeping sickness) are going to make colonization a nightmare, and more importantly, expensive.
Even if the settlers don't die, good luck setting up basic infrastructure without cattle and horses (both of which are affected by the tsetse fly) to do the heavy lifting.
The best candidates for this sort of thing are places that are already fairly lowly-populated. The more arid portions of Southern Africa (i.e. OTL South Africa and Namibia) are prime candidates for this, as others have said. They can (and did) sustain European settlement far before other parts of Sub-Saharan Africa. Pastoral, nomadic peoples in-general, are something that after a certain point will be extremely vulnerable to the expansion of European colonies (and thus sedentary settlement).