I can't compare the two, you lost me is one of xtinas more restrained vocal performances while beyonces is a lot more exagerated, at this is in beyonces prime vocals and when xtinas voice started to get a bit shaky.
"You Lost Me" is the better song and delivers the better vocal. Not only does Xtina deliver the better vocal as far as sound goes but she also portrays her emotion better in the song.
