Who needs to work more on their voice? This will be judged purely in the present. SO, if a singer had an amazing voice in the past but has deteriorated then pick that one.
All of them but Madonna (She had vocal lessons in the 90s before Ray of Light.) Btw, getting vocal lessons doesn't mean you're a bad singer, it just makes you a better vocalist.
I don't get why Xtina? I know she tends to over sing but I think she has a good voice??
I voted for Katy! I mean....I just don't understand it, she is just awful IMO
I know no one's going to agree with me, but Adele. I find her live performances disappointing. The first time I listened to the Royal Albert Hall recordings I was pretty surprised. She has a fairly powerful voice (but a very overrated one) but that doesn't make it perfect.
I don't think Xtina needs a vocal coach, she just needs to stop screaming and trying to impress everyone That's just a conscious decision she needs to make.