These two divas are always compared on many aspects, so... who is more original? Consider music style, lyrics, fashion sense, performances, videos, photoshoots, career choices...
I know not many will agree with me but I think Katy. No one has ever pulled off quirky-colorful like her (Kylie is the closest tbh), and as someone else pointed out she is never accused of copying anyone else.
Overall though...
Music style - Gaga
Lyrics - Katy
Fashion sense - Katy
Performances - Gaga (VERY close, though as I do think KP puts in a lot of effort to her performances)
Videos - Katy
Photoshoots - Katy (I have always been very disapointed with Gaga's photshoots)
Career choices - Katy - that bitch knows business!
Remember this is purely originality though, overall I still prefer Gaga.
The one that actually copied the other, colouring hair with bright colours/ wearing colourful wigs, covering a song, follow the other's footprints to be more outrageous blah blah is less original
When you think of Lady Gaga, you think of a very specific artist, but when you think
of Katy Perry, no other artist really comes to mind, therefore Katy Perry is far more original.