Thats getting into some sketchy comparisons, SmokinLoon, the Panther is better than the Tiger I in many areas, but the Tiger I out preforms the Panther in others and under specific conditions. Overall, I would consider the Panther a better tank, even if the IS was a better HEAVY tank.
And I think the IS-2 was better than the Tiger I, even if just barely, and only because of its increased armor. But that a German 1942 tank is comperable to a Soviet 1944 tank is really telling.