F9's international rates for some popular destinations have increased by 40% recently, e.g., China was 1c/min, it became 1.4c/min. CWU has consistent less than 1c/min, CC is like 1.3c/min.
I tried to compare international rates of several providers, only F9 doesn't have A-Z table.
F9 customers recently complained about without rate table.
Providers with A-Z tables have more transparent rates and are less likely to have problems F9 had.
As you said, rates are not the only factor for customers to select providers.
I currently have much more reputable providers with lower cost.