I thought they taught this stuff in middle school.  You're right, a feather will take longer, because of air resistance.  Take that feather and turn into a little ball, same mass, and still much lighter than a golf ball, they'll hit the ground at the same time.  Gravity is constant, it is always the same, and mass has no effect on how fast things fall, everything falls at the exact same speed, when you take away air resistance.