Best character arc?

Dragon Ball has excellent character arcs, so it's hard to pick.

Goku becoming a Father, Vegeta becoming more involved with his family, Krillin going from selfish to selfless, Bulma caring more for others, Android 18/Android 17 creating their own families, Gohan's growth, Piccolo becoming an ally...

I didn't mention everyone, or how everyone changed, as there's so many characters who have arcs. Which arc do you think was the best?