My overall opinion of Oro: First, Itachi said himself that even if he and kisame together were to fight jiraiya, the three of them would die, and Jiraiya said that he has never surpassed orochimaru. Stats don't mean everything; Asuma's stats are higher than Hidans but Hidan completely swept the floor with him. When Oro and jiraiya both fought, neither of them could fight at full strength, and Oro was at the much larger disadvantage; he basically fought Jiraiya with his tongue and taijutsu, and was still winning. This suggests to me that Oro is stronger than Jiraiya, or that they are at the very least equals.
Oro was trying to posses Itachi, and when he does this, he is usually ill and goes into snake form and he can't do major harm the body he is trying to posses. Itachi and Orochimaru basically battle in which itachi could go all out and oro couldn't, so yea, itachi won. And it says in the manga "itachi is stronger than me" but it never said which form, in snake/possesion form, in which he is pretty weak, or in his normal form, in which he's crazy powerful. Also, Oro played around with Naruto in 4 tailed form (oro had his jutsu back but his body was weak and rejecting him at the time) while jiraiya almost died, however, Jiraiya, being Naruto's godfather, probably didn't want to hurt Naruto.
Overall, I think that Oro and Itachi are at least equally powerful, but I think Oro is stronger.
And Sasuke was in no way near Oro's level, during the time he "defeated" oro. Oro was dying in bed from sickness when Sasuke attacked him. Anything could have killed oro at that time, he was freakin' dying! And sasuke said that he would not have dared to challenge oro if that weren't the situation. Sasuke as he is now... I only watch the Anime, and Sasuke's last appearance was when he defeated danzo. I need to see sasuke more to say wether he is stronger than oro right now or not, but at the time he "defeated" oro, sasuke didn't stand a chance. My bet would still be on Oro, though.I just hope that if they do fight, plot continuation doesn't interfere and somehow allow sasuke to win, like it did with Deidara. I think the writers just needed deidara dead in order to continue the story, because if deidara didn't suddenly get all pissed and just used a smaller bomb instead of blowing himself up, he would've killed Sasuke.