On earth, a feather would weigh the most at the North Pole because the value of acceleration due to gravity at poles is 9.863 ms-2, whereas at the equator is 9.798 ms-2 and weight of an object equals the mass of the object x the acceleration due to gravity so, weight increases as one moves from the equator to the poles.
Outside the earth, feather weight on Jupiter is the most due to its stronger gravitational force as it's a much more massive planet than Earth.