In no way am I saying one would beat ther other in fight. Its just my opinion that these 2 are equal. While we all know that itachi was a prodigy. Sasori defeated, whom most considered the strongest kazekage, at age 15 I think, who also had a kekkei genkai: Iron sand release. I think feat alone makes sasori a prodigy. If you look at their respective fights, sasori vs chiyo and sakura and itachi vs sasuke, they both let themselves get killed in fights they could have easily won. If I did an akatsuki list it would go like this:
1. Tobi
2. Pein
3. Itachi/ sasori
4. Deidara
5. Kisame
6. Kakuzu
7. Konan
8. Zetsu
9. Hidan
1. Tobi
2. Pein
3. Itachi/ sasori
4. Deidara
5. Kisame
6. Kakuzu
7. Konan
8. Zetsu
9. Hidan