Im definitely team general SA over Amazon.
Getting an amazon animal pack sounds great at first, but if you take a closer look you notice that alot of the animals people want from south america actually dont live in the amazon basin, or just range into it ever so slightly so arent really a natural fit.
Black howler, golden lion tamarin and geoffroy spider monkey, the three most requested primates for SA dont really live in the amazon.
None of the pink trio of ibis, spoonbill and flamingo really live there either.
Thats not to say that you couldnt do a cool amazon pack, as coati and ocelot still are a perfect fit and you could settled for a squirrel monkey or saki instead.
But i think at this point its better go for a more general SA pack so you can also include stuff from the tropical grass/wetlands, patagonia and other non-amazon forest regions