I’ll try to answer:
Parameters: - No large-scale conflict, internal or external, in the last 15 years; a growing economy; stable and fair elections; no mass population loss from emigration; per capita income over $10,000; low levels of corruption.
Successful black nations:
(Outside of Africa)
Bermuda
Bahamas
If trends in crime and economy continue for another 10 years or so, Jamaica could join it’s fellow tourist islands as a successful black nation.
(Africa)
Botswana
Gabon
Several other nations are poised to be added to this small group, like Angola and Namibia.
Successful South American nations:
Uruguay
Argentina
Chile
If Brazil would rid itself of a culture of corruption and Venezuela could get back to democracy, they could be added to the success list.
To your credit you did establish benchmarks.
As for these former Crown Colonies; Bermuda has a population around 65,000 and the Bahamas about 380,000; all imported from Africa. Not nitpicking, but are these really nation states???
Botswana is 75% desert, suffers chronic drought and is land locked. Successful???
Gabon? Probably yet poverty is endemic.
As for SA, disagree w/Chile and disagree emphatically w/Argentina and Uruguay. The bane of all three has been their impulse toward dictatorial rule; a condition that chronically resurrects itself throughout SA history.
In one of the ironies of history, Argentina was the 4th wealthiest nation on earth on the eve of the Great War due to its massive gold stock, as well as its thriving cattle, coal and wheat exports. But a succession of military strong men, such as Juan Peron, drove them into the economic ditch from which they have yet to recover.