This perhaps, I think a biased comparison. So I'll drop down some points I liked to both books since there's no basis for comparison here for me to vote.
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Storywise, I'll go to The Godfather.
Adventures and Drama, I'll go to both books.
Plot, I'll go to The Last Don.
Love Scenes, I'll go to The Last Don.
Values and Lessons Learned, I'll go both books.
Character wise, The Godfather.
"You can all go dancing on the bottom of the ocean." -Don Clericuzio
