It seems to me the ideal would be a combination of Edison and Tesla. There's no reason one person couldn't have both Edison's work capacity and Tesla's theoretical genius. Certainly many of the best scientists qualify: Newton, for example, or Euler. Euler was incredibly prolific---his lifetime output fills shelf upon shelf---and yet he was undeniably a mathematical genius as well. In music, J.S. Bach also fits the mold of incredibly hard-working genius.