At the height of his power he had all the edo army plus this Madara who shits on Nagato and Itachi.
The only reason I can imagine he didnt wanted to fight Tobi is that apparently the Madara summon takes time to activate as it was shown (yes he was summoned to Tobi before, but it an inactive form and it was shown it takes time for one reason or another)
Also take the fact that the attacks of Madara are basically nukes, he said "It would be troublesome to fight the Rinnegan HERE" it is possible seeing this another reason Kabuto didnt wanted to fight Tobi is because well he would be caught in the super attacks as well.
Even if Itachi deactivates Madara he wont be defeating Kabuto at all, because Madara is on the battlefield, this mean he will fight Kabuto personally, if Madara were summoned to fight Itachi then Itachi would logically get wasted against Kabuto + Madara, so it appears Itachi will defeat an edoless Kabuto.
Take in count edos are part of your own power.
So yeah, at least until Tobi gets feats it seems Kabuto is the strongest man in the manga right now. We have yet to see if Tobi is capable of attacks like that of the meteor which I dont think because he hasnt shown to have the EMS > Rinnegan combination Madara has to truly use the Rinnegan.
The only reason I can imagine he didnt wanted to fight Tobi is that apparently the Madara summon takes time to activate as it was shown (yes he was summoned to Tobi before, but it an inactive form and it was shown it takes time for one reason or another)
Also take the fact that the attacks of Madara are basically nukes, he said "It would be troublesome to fight the Rinnegan HERE" it is possible seeing this another reason Kabuto didnt wanted to fight Tobi is because well he would be caught in the super attacks as well.
Even if Itachi deactivates Madara he wont be defeating Kabuto at all, because Madara is on the battlefield, this mean he will fight Kabuto personally, if Madara were summoned to fight Itachi then Itachi would logically get wasted against Kabuto + Madara, so it appears Itachi will defeat an edoless Kabuto.
Take in count edos are part of your own power.
So yeah, at least until Tobi gets feats it seems Kabuto is the strongest man in the manga right now. We have yet to see if Tobi is capable of attacks like that of the meteor which I dont think because he hasnt shown to have the EMS > Rinnegan combination Madara has to truly use the Rinnegan.