Animal
Tik Tok was bigger than anything Katy Perry had out at the time and was bigger than California Gurls too wasnt it?
I also think, by era comparison, Kesha was more identifiable. Katy had two relevant singles obviously but she wasnt Katy Perry until Teenage Dream.
K$ tbh. The Animal/Cannibal (one era tbh) was huge (singles wise) and started in August of 2009 when TiK ToK was released and lasted well into 2011. The Epitome of debut longevity tbh.