Try those cities longest nonstop from original cities is:

ICN-GRU is 12150 mi
SIN-SJU is 10913 mi
MIA-SIN is 10542 mi
JNB-PHX is 10019 mi
JNB-LAX is 10385 mi
HKG-GRU is 11195 mi
HKG-EZE is 11458 mi

I thinks which specific routes is best longest nonstop from entire cities.