Basically, is Kaguya the better choice of becoming the final villain of the series over Madara Uchiha? For me, I like her more than Madara and I find her more... refreshing, like I did when Nagato was still at large, simply because they weren't Uchiha's. But in terms of a literary sense, even though I find Kaguya more interesting, Madara was definitely more in the right of claiming the title of final adversary. Why? Because he had epic foreshadowing. Even though he remained nameless until after the time-skip, his statue was seen at the end of Part I at the valley of the end.