The orientation of the patio canopy depends on how you would like to use your patio. If you want to install a roof over an existing patio, the orientation is generally pre-determined. With a new-built, the choice is up to you:
North facing: patio canopies get little sunlight or no sunlight at all; therefore, the space often remains relatively cool.
East facing: you can enjoy early morning sunlight and shade around lunchtime.
South facing: you can enjoy the sunlight almost the whole day.
West facing: patio canopies get the most sunlight in the afternoon and evening.