Belt(Lowest resists) - Light
Gloves(2nd Lowest resists) - Medium
Depending on the sets you're using it's often easier to use the monster set for the light and medium spots since they came in different types. If you're using a crafted set or one of the few dropped sets that come in different armor types then gloves and belt are optimal.
Most dropped sets come in fixed values, so if you use two dropped sets + monster you sholders is your best option.
Chilly-McFreeze wrote: »Head, chest and legs should be the heaviest bc they give the highest armor rating. Belt the lightest.