Kabuto stated he couldn't get enough DNA for SO6P, all the hokages are off-limits via reaper death seal. Chuck Norris doesn't exist in Naruto. I find it also highly unlikely that the current madara isn't the same one of the past. So from your list, cba to think of anyone to add, Izuna is the most likely.

I believe it to be Rikudo or the real Madara and as NearRyuzaki has said, it is impossible to bring the Hokages back now.

I agree that its between Izuna or Madara, but I chose SO6P because I'm hoping its him, I'd like to see his abilities as they are mysterious.

I am like... 98% sure Tobi isn't Madara. At least, not his body.

lol Chuck Norris.... I'd like to see that fight

So6P or a new person we haven't heard of yet. (who will be revealed when he is summoned again)

I picked the real Uchiha Madara because I was always curious about what happened to Madara's body because his body now is Obito's right? So, the real one or his brother, and maybe SO6P! <3 <3 <3