Think the M36 was called "the Slugger" and was a TD (tank destroyer), not a tank. The Pershing, if memory serves me right, was the M26. just a technical point.
My pick is the Panther. Just a really well made tank. Almost perfect balance of power, armor and speed. Gun was outstanding and very effective for it's size. So well designed that the French kept making them after the war to use in their armoured vehicles.