Obviously Gaga. The one who sings better- both live and in the studio. The one who takes even small risks, rather than putting out the same kinds of things over and over. Most of OOTB is unlistenable (although her best song is on it!), TD is pretty good, and PRISM is disappointing beyond belief.
Someone brought them up to try and act as if they determine who has the better music.
But Katy still makes better music
In my opinion she has good music, but I feel like Katy never gonna grow up musically. That's why I think that Gaga has better music. TF, TFM, BTW and ARTPOP are completely different