Z version: "You can destroy planets, but you can never destroy what I am, friend! I am the hope of the universe. I am the answer to all living things that cry out for peace. I am protector of the innocent. I am the light in the darkness. I am truth... Ally to good, nightmare to you!"
Z Kai version: "I'm the Saiyan who came all the way from Earth for the sole purpose of beating you... I am the warrior you've heard of in legends. Pure of heart and awakened by fury, that's what I am! I am the Super Saiyan, Son Goku!"