Tough question. I interest to try to answer it. Ok, tight your belt, here we go.
My parents feed me for years, they suffer for me, spend on me, while I never give them anything but a headche as a child and teenager. My mother pregnant me for 9 month, and birth me with horrible pain. They give everything they have for me and they don't need anything in return. If I die for them, I don't know if that will be equal with their effort on raising me with their love, affection anything they have and had.
While my childern. I love them so much, they are my blood, they come out as a part of me, but still, man must know how to return the good deeds of other, especially parents.
In this case, I choose my parents.
But still, it is easier to said then done.