I wouldn't know who that person is. Perhaps the Buddha could have known this by using his psychic powers. How do we know the levels of suffering of people? Even if they're suffering the most physically, they may not be suffering the most mentally. Someone who is suffering from mental Dukkha, may be suffering more than someone who is suffering from physical Dukkha, because they don't have the mental capacity to deal with whatever it is that is arising for them, they don't have the mental capacity to deal with the Dukkha of life.
So it's very difficult to pick out someone and say they are suffering the most, but even the person who is suffering the most has the capacity to end their suffering.