Panther was horrible, because it had many mechanical issues and was a pain to fix, ammunition stores were vulnerable, and many would just break down in the field, generally being overengineered.
The T-34 was also horrible, because it's armour was very brittle, and the plates often didn't fit together. The gun was mediocre, but no better than the Sherman's. The suspension was also complete rubbish
The Sherman was actually good