They would get along, but I feel I should point out that rasboras are Asian, not South America, so if you want a 'real' Amazonian biotype, you wouldn't have those
As for what's 'best', well that depends on your taste.
Rummynoses are probably the best schoolers (ie, they swim in a coordinated manner, all together); other tetras tend only to school if they feel threatened or scared, so will usually just form a loose group.
I, for instance, really like blue fish, so I have blue/green/false neons (they go under various names;
Paracheirodon simulans anyway) in my Amazonian tank.
If you like red, then a large shoal of ember tetras, or red phantoms, would look gorgeous against the green plants. If you like blue and red equally, then cardinals or neons would also look lovely