What is better Static or Kraken?

I was watching a friend play league while I work on something and I saw that he build Kraken on Kai’sa first. Which made me ask why he build it and not Static. It boils down him not liking it and it doing more single target damage then Static. I personally think static is the better item to build on her as it gives her evo faster and is a cheaper item. So I want to ask which is better Static or Kraken.