im gonna say GDP all the way if it's the ken cut......Ive grown out the Grape ape...its good but its something special about the GDP in my eyes... but I may like one and you may like the other....if your friend is growing out GDP then grown out Grape ape then just trade some buds if you trust his growing skills... to see both...and then next time grow out the grand daddy....i bet you keep the GDP....or hell grow out the GDP with him and compare his skills with yours and sees whos better lol
but it just depends if you like Pepsi or Coke....(not that they taste like soda...but you get the picture lol)