This choice should be made by the victim. The victim should choose the option which makes him/her feel good.

Both are important. It depends on the circumstances. Justice is important when it helps to correct a bad situation or punish a wrongdoer or criminal for a crime committed. But mercy is needed when a persons sincerely feels bad for the trouble he has caused.

Both both of them complete each other , if the person doesn't have mercy how could he or she applies justice ? . Justice Without mercy is cruelty , and mercy without jJustice is the mother of dissolution . And Both of them consider as a main part of ethics , so they can't be separate .

I think that merciless justice is better than unjust mercy

Justice is more important than mercy. Through the justice we find the real mercy which we need to keep our rights. Justice means that all people are equal in their rights and duties . mercy gives a chance to prefer one to another.