I press my seams to the darkest fabric unless the construction of the blocks demands the seams be pressed differently.
There are exceptions when the seams do need to be pressed open to reduce bulk, like when several seams meet.
When seams are pressed to one side the seam is stronger because the stitches are hidden in a seam. When seams are pressed open the stitches are more exposed and not as strong.
Generally garment seams are pressed open and when someone moves to quilting they want to continue pressing the seams open. The quilting way is to press the seams to the darker fabric.