Xtina has a way better tone, tho she's not been officialy trained she does descent when it comes to belting, but yeah, she cracks a lot. Beyoncé has better control over her voice since she has been trained for so long, duh. Kelly? well she deffo can belt and she's a nice tone.
Overall, I think I'll go with Xtina because of her tone and passionate performances, as she once said, there's beauty inside imperfections, she deffo would sound lot better if she stops her oversinging but oh well it's a trademark alreay

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