Itachi would win obviously, even Madara said he'd be dead if itachi wanted, itachi was diseased, gave his power to naruto, and had no intent of killing sasuke.
His powers hasn't been revealed, so they must definitely be better than someone who's completely invulnerable and can seal away anything with a swipe!!
Itachi won the fight he wasn't even trying to win. Well would have had he not died from the disease anyway. If he was trying to kill Sasuke it wouldn't have lasted long at all.
__________________ If you try something stupid, and it works it ain't stupid.
im not saying that, but sasuke has already started and STOPPED amaterasu. many people beleive that he already has all of itachi's mangekyo jutsus. he also has said to have the power to destroy konoha. so basically, every advantage that itachi cud have posessed is gone. plus that whole shaaringan telepathy thing. also, have people forgotten kirrin so quickly, the ONLY reason itachi survived was because of susano. kirin might even be greater than amaterasu.
The only reason Sasuke got to do Kirin is because Itachi didn't kill him right away. And Itachi can do Amaterasu willingly and without pain.
Having all his jutsu doesn't mean Sasuke is even equal to Itachi (not that he has all of them probably). The person who mastered them and is more powerful. And he blocked Kirin once he could do it again.
__________________ If you try something stupid, and it works it ain't stupid.
Maybe because he didn't fall to his knee holding his eye. Nor is it being forced out of the wrong eye without Itachi's wishes while Sasuke's has never been used willingly it was a safe-guard once, and unexpected emotional thing the second time. Itachi would be able to use it a lot faster. And in a forum fight he wouldn't be going easy on Sasuke. Or ya know Itachi could just use Susanoo again and kill him while Itachi is compelely unable to be harmed.
Itachi is still the smarter of the two, and the stronger of the two.
The same can be said for Itachi. He stopped Amaterasu when he used it on Sasuke. Or the clone anyway.
__________________ If you try something stupid, and it works it ain't stupid.