Madara would win. He's clearly the strongest character shown in the series so far aside from the Sage and possibly his two sons. He was able to react to Raikage's attack meaning that he isn't greatly outclasses in terms of speed. Madara's Rinnegan abilities will enable to absorb the chakra of any ninjutsu Killer Bee might use against him and his Susanoo will protect him from most of their attacks. And if all five Kages are needed to fight against Madara, I doubt Raikage and Killer Bee will be able to defeat him. Madara could simply bring down two meteors again if he wanted to since the technique has no visible strain on him. Not to mention that he can use Wood Release and most likely other techniques we haven't seen, for example, we haven't seen him use Amaterasu yet.