More of the 3 Sannin.
Uzumaki Clan
Hidan/Jashin
for me, it would have to be:
- Prime Hiruzen fighting flashback
- Hashi's Death
- Tobirama vs 20 ninja death
- what happened to senju & uzumai clan
what about you guys?
Everything Kisame, Kakuzu, Senju Bro's and Bee related
The flashbacks we got from them were a joke, some tease shit, I mean cmon look at how dedicated he was to Obito and his flashbacks -_-
Orochimaru's backstory
Orochimaru conquering the Land of Sound
Backstory of the Sound 4
More of the Sannin
More of Hiruzen and Danzō
How Tobirama's reign went
What sort of people and powers the clans besides the Senju and Uchiha had in olden times
The war that caused Kaguya to eat the tree's fruit
And a lot more
Uzumaki story
More development for the hyugas
Shuisui going ham with cheese