Madara. I wanted to see him being happy with his bf Hashirama, seeing how things turned out in the end. Going out to have fun. Going on shoppings, on trips like skiing and doing radical sports.
I would also want his mother to be revived so we could see them talking, and see what talks about the Senju and how much she felt sorry for her son. His older brothers would also be by his side playing with him.
I wanted to see him being respected at last by the clan he cherished so much.
I wanted to see how him and Izuna bonded over the time too.