Along with Madara, he was the first Uchiha to awaken the powers of the Mangekyo Sharingan, which he did by killing his best friend.

Source: https://www.cbr.com/naruto-strongest-weakest-mangekyo-sharingan-users/

Despite his efforts being in vain initially, Obito did not give up as he earnestly fought against Madara to help the Allied Shinobi Forces.

Source: https://gamerant.com/naruto-were-obitos-actions-worthy-of-redemption/

Despite his rivalry with Kakashi, Obito had no darkness in his heart until Madara saved him from the collapse.

Source: https://www.cbr.com/naruto-madara-best-quotes/

He was acknowledged by multiple strong individuals as a shrewd tactician and was even deemed to be a problem by Madara Uchiha himself.

Source: https://gamerant.com/naruto-most-intelligent-characters/

He was so strong that he was always one step ahead of Madara, and his cells were highly sought after by many ninja including Orochimaru.

Source: https://www.cbr.com/naruto-strongest-clans-ranked-by-strength/

Most would argue that the retcon improved the story overall, allowing Hashirama and Madara to become centerpieces to the plot.

Source: https://gamerant.com/naruto-the-minato-retcon-explained/

On the other hand, Hashirama does not give up on peace and urges Madara to stay.

Source: https://www.cbr.com/naruto-brutal-intense-fights/

"The Rinnegan cannot be awakened without possessing both Uchiha and Senju powers," Madara explained.

Source: https://screenrant.com/naruto-rinnegan-explained-madara-powers/

The talented artist shared their brilliant fanart on X, showing off their incredibly detailed, clean, and creative interpretation of a brutal battle between Marvel's Thor and Naruto's Madara.

Source: https://screenrant.com/thor-vs-madara-unites-naruto-marvel-avengers-fandom-fanart/

Tobi/Obito helped create the Akatsuki to fulfill Madara Uchiha's goal of plunging the Earth into a permanent dream world.

Source: https://www.cbr.com/naruto-all-akatsuki-members-in-order-deaths/