Well, I've been to both of them and i really love these two artists a lot. I always had a special place for Gaga in my heart, but i became a fan of Katy with Teenage Dream. But I prefered the artRave. Gaga actually performs for the crowd and I didn't felt it from Katy. I enjoyed every part of Gaga's show, but some parts of Katy's show were kinda boring. Gaga doesn't care who will be in the audience while Katy did some parts way more childish. But I really loved the acoustic part from the Prismatic Tour, which I kinda missed in the artRave. But I still like them both and their shows too. :)