It's kind of hard to choose for me. I like Deidara becasue his fight style is mostly from mid to longe range, but Sasori has the same fight style.
I probably gonna go with Sasori because when his puppet attacks is going to be hard for his oppenents to dodge espically if his oppenent is a close range fighter. Also his puppets can peform plus rapid,consecutive attacks than Daidara can. (And Deidara takes a moment befroe he attacks agian, while Sasori's puppets can attack rapidly,and constantly)
there is no question about it sasori's art is way better, what he should have done was kill deidara, and turned him in to his own play thing. i don't know how deidara even got one the team. him and his cute 80's hair.