HONESTLY HE IS NOT OBITO. Jeez. Just the fact that Madara looks like he's older than Jiraya shows that he can't be Obito, who would be about Kakashi's age. Also, WHY IN THE WORLD WOULD ZETSU SAVE HIM??? There is no reason to save someone who's given away a sharingan and had his other crushed by a rock. Also, his change of heart is quite radical, if he were Obito, wouldn't there be ANY sort of interaction between he and Kakashi? And also, just because Tobi lied about his identity and lied to Sasuke about Kurama's attack doesn't mean that you can't believe him. What he says he says with a purpose, not just for the heck of it. When he lied about who he was, he did it just to spread the fear of the name Madara. When he lied to Sasuke, he was trying to get Sasuke on his side. There is no reason for him to have lied about anything else that he has said. Also, where would he have gotten his sharingans? Zetsu certainly wouldn't have any at his disposal, and he was missing two. Finally, it would make for a terrible plot twist and Kishi would never do something so ridiculous. No, Tobi is 100% not Obito. But continue speculating all you want!
It doesn't seem to me that Tobi is anyone in reality. If anyone, I would say he's either Madara's brother or some weak shell of Madara, although that doesn't explain why Tobi needed the Rinnegan transplanted, since he would have already had it. Tobi may be Madara's brother because he knows much about the past of the Uchiha, and he would have obviously lied about his death to keep the confusion constant. Madara may have kept Izuna alive and provided him with new sharingans. But all ideas are flawed in some way. Just the Obito one is just impossible as I see it.