As per the Scrum Guide team should work collaboratively.
You have work items A,B,C X and Y with same priority to be delivered.
You have 4 developers in your team.
Developer 1- Because of his skill set he can work on A or B
Developer 2- Because he has done similar work in some other organization he is the best candidate to work on C
Developer 3- He is more experienced and can work on any of 5 work items.
Developer 4- He is junior and more willing to take work of low or medium complexity such as X.