From what i heard itachi is stronger then both of them.. actually i think he is the strongest PERSON in the naruto series , and it even kinda makes sense.. just think about it , he killed the entire Uchiha clan when he was a kid , because we can see he is not more older then sasuke , so maybe he was like 13 when he killed the entire clan!
just think about it...killing an entire clan..its almost impossible , because lets comapre for a second the Uchina clan to the Hyuga clan , from what we saw so far about the Hyuga clan , we can see it has Jounins , Chunins , Genins and probably a clan leder who is very strong , so probably also the Uchiha clan had also those kind of stuff.. now think about it.. a kid who is like 13 .. kills an entire clan..which includes Jounins , Chunins and etc...thats insane.. that's why i think Itachi is the strongest , because if in that age he could kill Jounins.. think what he could do now.. he also looks so cooool..because he have 3 dot sharingan in his both eyes unlike sasuke who has only 2 dots , so i think hes really insanly powerfull and i just cant wait to see him he will pwn the hokage , oro and that gay jiraya who i cant seem to understand why everybody likes