The Biggest problem with Tobi = Obito is the Timeline and this:-
If The above is True, The Tobi Cannot Ever Ever be Obito. Tobi <> Obito.
Now Tobi=Obito fans will rush to claim that Tobi is a liar. Well right now I can't prove his veracity on this matter, but we are getting closer and closer to the truth. We'll find out soon enough.
Also looking at the page below:-
Kabuto knows that Tobi is not quite exactly literally Madara. Tobi also knows that Kabuto knows. Yet, Tobi INSISTS that the Rinnegans were "Mine to begin with"
Assume for a moment that Tobi is not Lying Lying Lying, actually I don't think he lies much except if it's neccessary to manipulate someone essential. Tobi Could be telling the truth to Kabuto and Konan if:
1) a part of him really is Madara
2) if he is Izuna, the Madara Took his eyes from him, the eyes that became Rinnegans are quite literally Tobi's eyes.
From now on and until the TRUTH comes out, My Chice is Tobi = Izuna ( Or an aspect or piece/part of Madara himself). I hope Kishimoto also explains the matter of Tobi becoming Complete.