Quoting Almightywood

I guess I would have to agree with the fact that Kagami Uchiha would be a good choice to be Madara based on ties with those involved, and Konoha political knowledge.
I don't really think it is him though just because there is way too little talk and or history about him. I'd like to think that if it wasn't Madara that whoever it was that's masquerading as him would have been previously mentioned as a rogue ninja or the like to have given us clues more or less.
That's just what I want though, doesn't mean it will go that way.

Thank you Almighty...then that makes my explanations more closer to an accurate event....This Kagami Uchiha is so the basis of my theories...but then again...it has some flawed in it...question is...If it was really Kagami Uchiha..Y chose 2 train under Nidaime Hokage...whats his purpose in doing so...what shall he gain in doing so.... but still My 50% of explanation goes for Kagami Uchiha...

I would like to point out that in manga chapter 510 that Madara used izanagi on Konan, and now Madara is using the rinnengan instead of a sharingan. since we have seen Madara teleportaion type justu is possible to assume that in the fight with the first hokage he simply teleported back to his hideout. and if madara was really died the first person i see going after his corpse is Orochimaru but he didn't I should i say couldn't

^ Made me sound like a super nerd lol

Also in the same chapter Madara talks about how he gained access to the first hokages abilities the only way people have been know to gather his abilities are through his cells, or maybe Madara has another trick in his sleeve

@Almightywood: Now that u mention it they do have the same hairstyle ............Hmmmmmm

Thanks for the awesome explanation guys...!

Madara is not obito or using obito's body...what I think is that he may be one of the suspected character ... he might be kagami uchiha.... what I realised by chapter 490,kabuto summoned again another character,but did not showed in the manga,tobi looked so shocked with it...so who is this one that kabuto summoned?

i think it is the real madara cause tobi was shocked or more like feared

because,even almost all the villages already know that tobi is madara,he's not taking his mask off(though it is not a big deal ).....i think tobi is not the real madara specially not obito...he might be one of the least suspected characters too

This is a good discussion. Obito posing as Madara is ridiculous. Madara gaining the abilities of the first hokage thru genetic manipulation is highly plausible. Could it be Izuna? I doubt it.

I'll stick with Uchiha Fugaku(Sasuke and Itachi's father) is made as container of Madara for now.
Reasons:
- Itachi said Madara is nothing but an empty shell of his former self
- Itachi made a desperate move as transplanting Amaterasu to auto-activate whenever Madara tries to reveal his face to Sasuke
- Itachi's conspirator in the "Uchiha Massacre" is Madara. Its not easy to massacre an entire clan of Uchiha considering most of them have their Sharingans activated(especially the Police Force) unless of course they have complete intel on all of the members of the clan. One person has access to these info and that is the chief of Police Force. The body of dead Fugaku can be a Zetsu clone.
- In the flash back, the top secret labor day of Kushina was leaked to Sasuke's mom which COULD be the reason why Madara took the chance to attack at the right time.

At the end of the day, this is just an assumption of mine. I can be wrong but who knows i might hit a jackpot

Fugaku does make some sense too.
If he was in on the whole Uchiha slaughter (as in Itachi's superior) it would explain the strained relationship between the two before the incident.

The difference in appearance (especially hair) is quite pronounced though.
To me this is significant because the only thing that really makes me question madara's identity is his appearance (his hair basically). The original Madara had long straight spiky hair, whereas this Madara has short curly hair. Fugaku also had straight hair.

All of his actions and words seem worthy of being the true Madara though (well maybe not as tobi, but cover ids are just that)