@Idasca Well, out of that three Petrosian seems the most dubious to me. Many players come to mind that probably were more relevant like Reshevsky or Bronstein or Nimzowitsch or Capablanca or Euwe.
UnpOPuLaR OpiNIoN: Magnus would destroy both Fischer and Kasparov in their best years, simply because of a) opening preparation, b) because he is better