hmmmm. gravitational or magnetic. hmmmmm............... well, since the gravitational field is affected by density and mass(but mainly density), and the magnetic field isn't.............. I'd say it's like comparing an orange and an apple. both are fruit, but the work in different ways. in essence, inconclusive at this point, but my opinion? I'd say the gravitaional field is stronger. why? because the moon is kept on orbit, not because of the magnetic field, but because of the gravitational one.