I admire you trying to solve this however if anything you have rekindled this war.
I've come to the conclusion based on those i respect (not on here obviously) and claim they are equals. Both are fan pleaser's, mary sue's. They aren't as strong as hashirama/ems madara however kishi has made their skill level nearly unrivalled, therefore whenever you pit two mary sue's against each other it never ends well.
As for Itachi thinking Obito is Madara it makes perfect sense.
Madara's hype is over 9000 in the manga and time his name has been called upon even kage level ninja's are in awe. After all "The power is in the name" - Tsunade.
However out of all these people who have been awe of madara's hype they have based this on stories and what not. The only person who could truly give a verdict on whether madara = obito is an uchiha due to their backgrounds and ill explain.
The 9 tails fox attack was believed to be a natural disaster. Minato/kushina obviously didn't because they experienced it. Later Jiraiya started to doubt this.
The MS is an extremely rare doujutsu and so far the only people we know that had activated it were:
Madara
Obito
Itachi
Sasuke
Izuna
Shisui
Shisui was confirmed dead so he would out of the question. Sasuke didn't have the ms till later on. Izuna was confirmed dead. Obito was confirmed dead. Madara was apparently dead
The uchiha know in depth their ocular power and the ability to subdue bijuu, this ability granted by the ms. So far the only uchiha who had accomplished this feat was madara.
That was the first hint to itachi believing it was madara because of his uchiha roots and in depth knowledge of what his ancestor is capable of doing, more so than anybody else outside the clan who have based his hype on stories. Minato came to a similar conclusion because of this feat. That feat alone along with the fact that during that time the known ms user's were either considered dead or had not awakened it.
The second feat which convinced itachi that it was madara is because of what tobi was able to do. Obito was able to get passed uchiha barriers and even know their meeting place. Who else would come to an uchiha's mind than their ancestor. Similarly obito bypassed konoha highest form of barrier technique, dispatched anbu and knew when best a jinchrucki's seal is at the weakest, this also made minato consider madara.
Madara being alive is something that would not surprise an uchiha because if they know enough of uchiha kinjutsu and their doujutsu powers wouldnt be far fetched for them to believe that the greatest uchiha who would know how to use either izanagi/izanami and was the first person to activate the ems therefore decrypt majority of the secrets of the sage could still be alive somehow.
To put it simple the feats that obtio demonstrated are feats that if an uchiha with great background on their ancestrey was to analyse would come to the same conclusion as obito being madara and that is a fair conclusion because obito was trained by madara. Madara poured his knowledge into obito who then was able to achieve a similar feat.
To an uchiha obito feat parallels madara's after all he was his sensei. Any other ninja outside the uchiha would not have the info to critically access whether it was madara or not because they do not know the secrets of the sharingan, merely base it on stories if anything