Calm is much more impressive defensively this generation. Calm is the set which isn't completely outclassed. Both should be ran with hazards, and the hazard setter is usually physically defensive.
If Bold Milotic is better on the team in question, you are better off doing something else with the team. Either using a different water, tweaking the team to make Calm Milotic feasible, or not using a water at all and filling your resistences + checks with different types.