Mercy--it's more rare and can make a more positive difference in someone's life. I think justice is hardwired into us---if I steal your yummy collection of forest-foraged nuts, your first instinct will probably not be to forgive , but to want your stuff back. However, if I'm a starving person, you may be the bigger person and show me mercy.
Now, most things we want justice for are not stealing nuts, but theft, murder, betrayal. Justice may bring some closure or some comfort to these things, but it will not bring back the sense of safety or the person you have lost. Mercy is more difficult, but we see mercy in the Truth and Reconciliation Commission in South Africa, a country that, though fraught with problems, has not erupted into civil war since the end of apartheid.
If justice were truly done for all those years of apartheid, South Africa would probably be in a considerably uglier scenario today. Perhaps if both Israel and Palestine showed each other mercy and forgiveness, that situation too would improve. You can also look at your own life---when justice has been done (and you were on the losing side), you probably carried that burden, perhaps longer than you should.
Sure, it was morally right, but personally damaging. (e.g. You hurt someone's feelings and they hurt yours in return). However, when shown mercy by the other person, you are being given the chance to make things right, to mend instead of retaliate or rot when the damage has already been done.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.