The .AFRICA is a gTLD so it might be covered by some dropcatchers. It hasn't a lot of development. It has around 62K registrations.
The .NG ccTLD is one of the largest of the African ccTLDs (154K) and it seems to be quite competitive. The .KE is also one of the stronger African ccTLDs (101K). The .UG is a small ccTLD (7.5K) by comparison to those two. I'm not sure that there is dropcatching in those ccTLDs as they have lower numbers of registrars.