1. Conor McGregor 2. Jon Jones ??? Conor McGregor by far has the strongest chin because he has never been rocked. He has been hit sure, but it's more like a "oww this hurts" but he is still fully aware of everything that is going on. If you look at the Nate Diaz or Mayweather fight, he gets hit and he gasses, but there is never a moment where he was in lalaland. Jon Jones has been rocked and put it lalaland, but he has also fought some heavy hitters at light-heavyweight. The fact that he never lost to Rampage, Cormier I would say is a testament to his chin.