P!nk at the moment. Not to discredit Kelly, but P!nk mainly has the upper hand with touring because she's much more of a performer. Kelly's peak might have been bigger than P!nk's, but P!nk has been more consistent.
Besides Kelly is big in the US, I am not sure about other countries.
And the only song i knew Kelly from (before ATRL) was Because Of You (which slays btw)