Ah, you are asking me to choose the best jewel from the treasure trove of jewels.
Well, I could make a little list of the stories that touch me most to the core but here are a couple of them.
First is Arjuna chosing unarmed Sri Krishna as his charioteer instead of his whole army. It shows his superconfidence as a warrior and his superbhakti of surrender and friendship and complete trust in Sri Krishna. He does not chose Sri Krishna for any outer benefit, not even for securing the victory but out of sheer love and longing to be with him even on the battlefield. That is what makes his choice truly exceptional.
The second story is Sri Krishna’s help to Draupadi in the moment of crisis. It reminds us of the promise of the Lord to his devotees in the moment of every crisis provided they call and open to the Divine Grace with complete faith and surrender.
I also love the story of Uddhava going to Vrindavan to teach Brahmagyana to the gopis but coming back baptized into love. In fact all the stories of Sri Krishna are wonderful and that would make a long list.
Affectionately,
Alok Da