I think Deidara takes it, but not because hes stronger. The reason is that this is not Dragon Ball( where the strong always kill the weak ), this is Naruto where the battles are relatives and the weakest can overcome the strongest. Deidara just lost for Sasuke becasue of his admiration for the sharingan that he couldnt accept( jealous ), resulting in killing no matter what and how.
If he fought Kakuzo I am shure that the one who would think superior would be Kakuzo( cause he shure has lots of powerfull tecs, and I personaly think hes the strongest)resulting in Deidaras overcome with his unpredictables explosions tecs.