I think one thing people may want to at least consider is the summons. Itachi (based on what I know, which is sadly, only the anime), has NO summons. I think that, as of right now, we can't decide who is the strongest, because based on what we know, it's entirely circumstantial. They're all considered so vastly strong for plot purposes. Orochimaru is the semi-bad guy/Sasuke's teacher. Itachi is trying to extinguish the threat of the nine-tails fox demon, and Jiraiya is the strongest/Naruto's teacher. Following this train of thought, it's possible to think maybe Itachi will be dealt with before the end of the anime, and the anime will end with Naruto, under Jiraiya's training, fighting Sasuke, under Orochimaru's. Somewhere along the way, Sasuke could figure out Oro's plot and kill him, then maybe kill Jiraiya to piss Naruto off enough to want to kill him. He may even kill Sakura, to really push him over the edge.
I know I started drifting off topic, but I think it's a bit pointless to argue over these three. -If- they ever do get in a situation with them at their best and squaring off, I think -something- would stop them from finding out the truth. It seems the only one of these three set to really fight is Itachi, but that doesn't mean he's the strongest. JIra seems to be just there to train Naruto, and Oro seems to just be there to give Sasuke power until Sasuke gets sick of him and kills him.
Quick question; you think the summons can be affected by the mangekyo? If not, then I'd say, just for the hell of it, that Itachi could very well be at the bottom of this list, instead of the top. Otherwise, it's so close a match that it's not really worth fretting over.