Another apparent no-brainer: the higher the resolution, the more detail in your images. However, many people don’t realize that switching your aspect ratio could mean you’re cropping your images and lowering the effective resolution.
For example, many phones shoot with 16:9 aspect ratio by default to match the phone’s display, even though their sensors are actually 4:3. It’s not a negligible either crop either; you’re effectively making the sensor 25% smaller. The popular square crop yields the same loss.
Most Android phones and all iOS devices have a 4:3 sensor, but some devices like the G4 switch it up. You can find the native aspect ratio by looking at which setting shows the most environment in the preview. It will also have the highest final resolution.