at least christina sings live. no poker face lip sync
Not that I'm a Gaga Groupie, but every performance I've ever seen of her she's actually singing.
And she can REALLY play the piano...
and before she had her own record deal, she wrote songs for people like Britney Spears and Pussycat Dolls.
So... I'd consider her more of a "real" artist than Britney Spears or Christina Aguilara. When you hear that Britney wrote one of her songs, she means that she wrote some of the lyrics to that song, with help from her producers.
When you hear that Gaga wrote a song, it means she wrote or collaborated on the music AND wrote the lyrics.
(Not that I own or would buy any of the music she's put out thus far.)