Christina. I love both versions I first heard this song with Christina and loved it, the song fits Christina's tone more than Bey. Beyonce's is great too though.
i hate beyonca and she's so overrated BUT i think her version is WAY MORE CLASSY and SOULFUL than Christina's amateurish version which is all about screaming in every way possible "ha!"
Christina's version is just an alibi to shout :SOMEBODY PLEASE KILL HER !!!!
Beyond does a version that is simple and closer to the original version.
Christina can't sing anything without blowing it out of proportion and making it ridiculous. We get it, you're showy and a skilled vocalist, but the runs can be cut to about half their length and the shouting is completely unnecessary.
Beyonce FTW! Her interpretation is pure, clean, and enjoyable to listen to.