Doflamingo, speed is is great (it looks like teleporting or the CP9's Soru), is able to go toe to toe with Crocodile, has wires that cut through anything, he can control Sasori without him seeing anything.
Dolflamingo. We know that he is the strongest of the Shichibukai, but have not seen all that he can do. With that being said, he seems much more formidable that Sasori, who was beaten by Chiyo and Sakura.
@Jflash94: Maybe but Sasori wont be able to see the wires all doflamingo has to do is point and he cantrols every part of Sasori's body and it's almost instant. Not to mention when Sasori send puppets at him he can just flail his arms and dice them up however, if Sasori gets the first move then yeah he stomps this battle.
@Kurohige: You underestimate Sasori. Control wouldn't work because he can counteract it with his own puppet technique. Also the poison gas and the needle storm may prove dangerous. Anyways I think he would lose in the end do to the obvious difference in physical power and the cutting wires were quite effective against Sasori when Chio applied them. Doflamingo wins though if he underestimates Saori he would pay very dearly.