Usually better rates in the country of the target currency.
Easy to change at the airport in Manila. In the city, use Google Maps to look for Sanry and Czarina, the 2 bigger FX changers. Changing money in the banks in Manila is not worth it because the banks take so long
There are 3 terminals at NAIA in Manila and all of them have small branches/counters of 3 or 4 banks right after you clear customs.
I happen to be staying in an AirBNB in Makati right now, and I recall there was a Czarina on the street level of this very building. When I walked out of the building this afternoon, I was surprised to see that the Czarina is gone, and I smiled when I realized it is being replaced by a Taiwan Bubble Tea shop