Oda seems to like to deal out the emotional scenes in two ways.
way one are the scenes where he will pound you over the head with a sledge hammer,
(Nami's History, Robin's History, Ace's Death, Rebecca and Kyros)
way two are the scenes where he will slip a dagger through your ribs.
(Robin meets the Revolutionaries, Luffy meets Sabo in Dressrossa, Robin and Aokiji talk on Water 7, Law's Backstory)
Which do you prefer?