Armstrong and Ornette should be at the top - they initiated the two most extensive revolutions in jazz. I'd then say Parker, Ellington, Young, Davis, Coltrane, Hawkins, Coltrane. Hines or Tatum? Roach? Fletcher H.? Blanton? It's probably true that a head count of pianists would now show more Bill Evans-influenced players than Cecil Taylor-influenced players, maybe even more than Bud Powell-influenced players.