T-34, no contest.
And forget about the Panther. The German answer to the T-34, it was so underpowered it couldn't even turn when driving backwards.
If we are talking about the early Kursk models, then yes; after mid 1944 the problems had been mostly been resolved. Although they were complex, the Panthers were probably the best all round tank in 1944 and early 1945. Many people overlook the fact some prototypes had been equipped with 88mm guns (Panther II) and infrared systems. The only fault of the Panther was that its good versions were not produced in large enough quantities to make any sort of difference to the war.