Thank you. What a great question. I believe that the strongest apologetic argument we will ever have on the subject of suffering is Jesus. God has not left us alone in our suffering but entered into humanity as Jesus Christ, brought compassion and hope to those suffering around him and then went on to suffer like us and for us through his death on the cross. No other worldview speaks of anything like this. No other worldview offers a diagnosis and solution to the problem of evil that rings true in the same way. To reconcile an evil world with a Holy God, in a sense we need a mediator. Like all mediators they need to understand the problem but not be part of the problem. Jesus Christ stands unique through history as the only person who did not contribute to the problem of evil, but instead came to defeat it. Jesus, who did, said and thought no evil ever, allowed himself to be consumed by our evil for a time, so that you and i never need to be consumed by the evil we face, either in this life or the next. Because he bore the weight of our sin, we are free to know the comfort of God in our troubles. Because of Jesus, evil does not have to have the last word in my life or yours. The demonstration that evil was defeated on calvary is the resurrection. Jesus did not stay in the grave but went through death and out the other side. And the same power that raised Jesus from the dead lives in us, meaning there is always hope for the trials that we face. However, deep the pit may be, God is able to pull us out and put us back on our feet again.
The strongest apologetic argument for suffering is Jesus. This does not necessarily mean it will be well received on every occasion. If the person is asking intellectual questions, then this may be leaping forward too far in the conversation. But if they are asking more personal questions and are open to the possibility that Jesus is proof that God cares for us, then the gospel of Jesus Christ begins to look like the good news that it really is.
Thank you for asking this question.