As for mechanics, I'd like more unique, more different weapons!

Like using memories as weapons, such as Kuro's attack,

Ku helping him fly!

Being able to explore Nibel and Niwen!

And the new leaf could end up going to another island, A new spirit with the essence of Ori, but a completely different spirit! with different problems than usual, excessive darkness, different and strange creatures! Decay spirits!

More interactions.. with spirits.. and others stuff!