If it came to an all out war between the puppet masters who would win! I think sasori would win because of his alterations on his body n his strong puppets with poison
Sasori already put Kankuro in hospital LOL if it wasn't for Sakura, he'd be dead. Also, Sasori is the creator of Kankuro's puppets so he knows everything.
Seeing as Sasori is one of the better Akatsuki members (Hidan, Konan and Deidara worse), and Kankuro is a noob who uses Sasori's puppets, I'm slightly, very sllightly leaning towards Sasori. Cant imagine why...