It's always about differing requirements.
GNG is interesting to Brazil precisely because it is still in development - ToT. Hence financial risk is better balanced against ToT value, than it was in e.g. Norway. The same applies to cost of through life support (upgrades, MLU)
Operational cost is (potentially) attractive to them.
Sth. Am. threat matrix is more predictable and manageable for the Brazilians than for other nations elsewhere on the globe.
GNG is not that interesting to some NATO air forces, because of interoperability (logistics, doctrinal).
It's a good choice, though I'm not putting my money on any horses in this race - I simply can't figure where it will go!