I voted left, but lefties may have a different opinion.
A good criteria would be tilt it to where the search field is, so it points to it. If the field is on the left, tilt it left; if it is on the right, tilt it right.
Seems the theory matches the answers. The number of people answering right matches the number of left-handed people on average. A very interesting point. Are we discriminating against left-handed people with those icons?