If we are to compare each in terms of talent, cultural impact, fanbase, diva power, superstardom, & awards, there is no question that GaGa wins. I like Katy Perry & toi may say that she's shit because she tied Michael Jackson's record of most #1 singles in one album but is that enough? Look at Rihanna & her 11 #1 singles; despite that fact, nobody really takes her (& her albums) seriously. Also, mind toi that Katy achieved her last 3 consecutive #1 singles from a cheap tactic to whore for the #1 spot on the Hot 100 (discounts + of course, re-releasing singles as remix in order to add plus hype into the single); That being said, I rest my case.
But since the question states who is "better" then it must be taken in a personal perspective & as for my case, Lady GaGa is better because Katy's achievements are nothing compared to GaGa's.
So was hard because I lv them both but they both have a great taste in style but Lady Gaga can go over the haut, retour au début what I like so the person I like the most is Lady Gaga because of her taste in style, bye!