Do enemies target the player with the highest number of souls?
Solution 1:
No, they do not.
The AI in the game do not focus on anything other than distance, and damage. The closer you are, the more they will focus on you, unless someone is dealing more damage, that outweighs their "distance" aggro.
Having any number of Souls, or your Soul Memory play no part in an enemies targeting calculations. The only thing that can affect this is the Redeye Ring which increases your "Aggro multiplier", making enemies aware of you over a greater distance, as well as reducing your "damage requirement".