I'm between Kagura and Tayuya, both of them are carismatic chatacters.

Kagura deserved to remain alive and became the next Mizukage in rhe Future to make justice for his father and prove that he could be a diferent leader.

But still, Tayuya has an undeniable carisma and i would choose her, if they spared her she could become an Konoha's ally.

Kagura.

Kagura's arc was completed with his death. As were Danzō's and Sasori's. Tayuya does not really have an arc, but I suppose that makes her the winner by default if they chose to give her one if she survived Temari's assault.

Kagura could have a Naruto-like route, becoming the Mizukage years later and removing the Stigma he suffered for being the son of a dictator.

And Tayuya death was like unecessary because Kimimaro pratically demoted her from sound 4 and Temari just Killed her on the Spot XDD