Shea Butter or Cocoa Butter?

I really want to get rid of my already silvery white stretchmarks but I don't know which to buy… Also, I was thinking of applying Vicks Vaporub on them at night with vitamin E oil and then washing it off in the morning. But using one of the lotions in the day. Any thoughts? If you had to choose between shea butter and cocoa butter, which would you go with?