which gps setting is the best to use for your galaxy s3?
Do you mean what location services?
If you check the VZW location services, that uses some info from Verizon towers to try to estimate your location. Some times as much as a mile off.
Google location services is about the same, plus it may use WiFi SSID lookup to get closer if you have WiFi on.
Standalone GPS uses the GPS and Glonass receiver to get you within a few feet if you have a clear view of the sky.
The first two use nearly no power. The third, the GPS receiver, uses power if you use a GPS app like Google maps.
Turn them all off and wear a tin foil hat if you are paranoid.
Be aware that even if you turn them all off, Verizon has a record of where you are from the cell tower logs.