Agree that Modric is better than anyone on Brazil's team. Mandzukic is a better forward than Fred too. Brazil should still beat Croatia due to their overall superiority in the squad and under the home conditions.
Not sure about Cameroon. African teams have stalled in progress since 1990. Some very good individuals but a general lack of direction among them.
Ivory Coast are probably the best bet out of the African lot with Bony, Drogba and one of the best players on the planet in Toure.
Nigeria tend to be very erratic in World Cups.