Reading on Kongo (the city, not the civ), it looks like a Religious or Cultural City-State. So it could replace Lhasa (Tibet seems unlikely), Vatican City (it'd be funny on an Italian City list), or any of the cultural CSs.
Frankly I think Mbanza-Kongo could easily be a maritime or mercantile CS - it was a trading center in the region and had connections with the Portuguese.
At the same time, it could also easily be a cultural or religious CS - it was an important place for the diffusion of Christianity.
It's too far from the sea to be Maritime, and reading from the Wikipedia article, it has a strong religious feel to it.
How does this sound?
Confirmed | Speculation
Lisbon → Riga Reason: Both Western/European Atlantic ports
Rio de Janiero → Panama City Reason: Both Western/Latin American ports
Warsaw → Bratislava Reason: Both Central/Eastern European
Budapest → Sofia Reason: Both Central/Eastern European
Marrakech → Mbanza-Kongo Reason: Both African
Jakarta → Ur Reason: Both Indian Ocean ports
Hanoi → Angkor Reason: Both Southeast Asian
The Zulu and Assyria did not affect CS distribution.
If we view a civs possible inclusion as costing a city state, some civs will have higher costs than others.
Timurids: -1 militaristc
You should also note that there is only one extra maritime city state that is unaccounted for.
Yes, Ragusa could be part of a Venetian city state list, but let's just be honest here, they aren't adding Venice as a stand alone Civilization. If they went for anything, it would be Italy, and whilst Ragusa is relevant to Venice, it's not to Italy as a whole.
Frankly I think Mbanza-Kongo could easily be a maritime or mercantile CS - it was a trading center in the region and had connections with the Portuguese.
At the same time, it could also easily be a cultural or religious CS - it was an important place for the diffusion of Christianity.
How could it be Maritime? It's no where near the coast.
If Mbzana-Kongo is mercantile, it could be a replacement for Zanzibar. Then assuming Ur replaces Mombasa, it could point to a Swahili civ. They try to keep the city states within the same cultural groups when they replace them and in both cases we have new Mid-East/African art-style cities.
Quebec City isn't on the coast either. Anyhow I thought Mbanza-Kongo was near the Kongo river or a tributary of it, though I might be wrong.
if Kongo is mercantile maybe it replaces Cahokia?
Why would it be Mercantile? It's a cultural and religious centre.