Just want to know peoples opinion.

We know he was lacking stamina, and Chakra because of his sickness but what if he didn't have it?
You must be registered for see images
Itachi would be the strongest Uchiha and Madara's equal. Madara has exceptionally large chakra reserves, much larger than any other Uchiha, so he would have more chakra, but Itachi's intelligence balances Itachi and Madara together. They both have Tsukuyomi, Amaterasu, and PS thanks to EMS. Itachi would easily be a very powerful Hokage and well suited to protect Konoha. But why should we ask what if Itachi had this and that? What makes Itachi amazing isn't what jutsu he has, or what eyes he has, or how his chakra and stamina are low, it's Itachi's intelligence that makes him amazing. Even with his sickness, he can defeat MANY characters with Genjutsu ALONE. I believe his power came from the desire to protect Konoha and Sasuke. Like my favorite Hokage said, "When a shinobi has something to protect, that's when a shinobi's true power emerges." - Sarutobi Hiruzen
He would be virtually unbeatable
I disagree. Hypothetically, let's assume both Itachi and Sasuke have EMS. It's an impossible scenario, but let's assume they both have EMS for the sake of discussion. EMS Sasuke would win over Itachi despite Itachi's intelligence. Sasuke can counter Itachi's Tsukuyomi since he can break through it, use Blaze Release to counter Amaterasu, and has Susano'o and Karin to counter Itachi's Susano'o. Nagato would still have a 50% chance of beating Itachi and Hashirama (if he was alive) would still defeat Itachi. Itachi's my favorite character, but I don't overrate Itachi like Kabuto did. Itachi wouldn't be unbeatable, but he would be incredibly difficult to defeat.
Stop being a Itachi fanboy. If we start to imagine, even tenten can beat SO6P
No. If we start to imagine, we can't make Tenten beat Rikudou Sennin. Even if she gets the Rinnegan, masters PS, masters all jutsu, and can utilize even Kekkei Genkai, she still would pale in comparison to Rikudou Sennin. Nagato was an Uzumaki with Senju lineage and had the Rinnegan. He had the potential to master the Rinnegan completely to master all jutsu and had more than enough chakra reserves and stamina to do so. His chibaku tensei was still NOTHING compared to the Rikudou Sennin.