An argument can be made for John Coltrane: the antithesis to Miles' "cool" sound. Like Miles, Coltrane was exploring modality, albeit with a characteristically denser approach to improvisations. That's not to say Coltrane couldn't play ballads, and Miles couldn't play fast. But to give reference, Ira Gitler (a jazz critic from Down Beat magazine) described Coltrane's approach as "sheets of sound". This approach is also reflected by pianist McCoy Tyner. There were many important figures in post bop, but the influence of Coltrane is so prevalent that he could be considered as "the answer".