Ninjutsu: Sasuke>Itachi
Taijutsu: Sasuke>Itachi
Genjutsu: Itachi>Sasuke
Intelligence: Itachi>Sasuke
Strength: Sasuke>Itachi
Speed: Sasuke>itachi
Stamina: Sasuke>>Itachi
Hand seals: Sasuke<Itachi
5/8 of Sasuke being better
Ems>Ms:
Amaterasu: Sasuke>Itachi
Tsukyomi: Sasuke<Itachi (but give it a few chapters and it won't be)
Susanoo: Ems susanoo (covered in amaterasu, has all of Sasuke's weapons) >= Itachi's ms susanoo with the weapons
If Itachi uses Izanami, He loses an eye. And if Itachi was slash by Sasuke's sword in order for it to work, Itachi would be dead. He's not immortal like Edo Itachi.
Itachi will lose eyessight in this fight ya know.
So it comes down to stamina, which Itachi poorly lacks in.
Itachi struggles to use 2 amaterasus, 1 tsukyomi, and one susanoo when he was alive.
Sasuke has used like 6 amaterasus, used to susanoo drastically and recklessly and still wasn't exhausted, and used Tsukyomi like once.
Sasuke fought the five kages with some help, yes, but he did most of it.
Sasuke has Tsukyomi, Amaterasu, Susanoo, Kirin, lightning style, hawk summons
Itachi has Tsukyomi, amaterasu, susanoo, kirin, genjutsu, crow summons
Tsukyomi and Genjutsu is useless against each one, so they must be taken away. Making Itachi's strongest quality useless, and Sasuke's weakest ems technique unimportant.
So now its:
Sasuke: kirin, susanoo, amaterasu, lightning style, fire style
Itachi: Izanami, susanoo, amaterasu, fire style
Izanami won't be used, because if Itachi gets slashed for the technique to work, Itachi is dead. Like I've already stated.
Sasuke: Kirin, susanoo, amaterasu, lightnign style, fire style
Itachi: susanoo, amaterasu, fire style
Ems susanoo>=Itachi's ms
Sasuke's amaterasu>Itachi's amaterasu
Fire style=fire style
Hawk>Crow
Kirin and lightning release are left for Sasuke.
Sasuke isn't that much stronger than Itachi (pretty close actually), but like Itachi is to Oro, Sasuke is Itachi's ultimate weakness.
Sasuke wins mid-high diff.