I think Sasori would win...
BlackRomaniac chill out, what's with all the hate?! I gets on my nerves when I see a kid getting so worked up to prove a point! judging by the respect they have for Chiyo it's very likely that she is a Kage lvl shinobi: sealing a tailed beast, coming up with a jutsu to bring a dead person back to life, the puppets, medical jutsu... she new Sasori way to well, so it was easier, also Chiyo clearly states that sasori could've dodged the last and fatal attack but just chose not to. Darui is great no doubt about it, it wouldn't be an easy fight for either of them but if I had to choose I'd go with Sasori.