My right eye, which is my master eye.
For those of you who don't now how to find out, hold your arms straight out in front of you and make a triangle with your thumbs and index fingers. Pick a focal point, place it in the middle of your hand's triangle. Now, while keeping both eyes open, slowly bring your hand in to your face while keeping the focal point in the center of your hand's triangle. You will find your triangle will find it's way to your master eye. Your other eye just provides stereo depth.