The USSR had a better military than Germany in WWII, the proof for this is the second part of the book The Rise and Fall of the Third Reich, in other words, the Nazis lost and the USSR won, in a conflict that was mostly decided by Armor clashes, like the Battle of Kursk.
Tanks are made to win battles and wars and the T-34 was successful while the German Tiger and the Panzer IV weren't.
However to choose which tank is better would need a definition of quality, or "what do you mean by better". To do a comparison to anther losing German vehicle, the Maybach brand, while having more luxurious and better engineered cars than Toyota, it was closed, while Toyota is the 12th-largest company in the world by revenue. Maybach, while having better engineered and more comfortable cars, had a price tag that was so high that (almost) nobody wanted to buy them, at the same time Toyota cars are selling like condoms in a cheap Motel.
The same happened with the German Tanks, While being superior engineer-wise they weren't easy to manufacture, and not suitable for war time economics. The USSR produced 35119 T-34 tanks and 29430 T-34-85 tanks in the period between 1941-1945, it's a total of 64549 T-34 Tanks produced in 5 years, while the Germans managed to produce only 1347 Tiger I tanks and approxematly 8800 Panzer IV tanks which is a total 10147 tanks in a period longer than what the Russian had. So the soviets had the sheer number advantage, on the Battle of Kursk The Soviets had 2.7 times more tanks than the German and on the Battle of Moscow the Soviets had 1.9 times more tanks.
The Military Channel did a "Top 10 Tanks" article, that named the T-34 as the best tank ever, while the Tiger and Panzer IV got the 3rd and 6th places respectivly, the reasons are the same as I explaned. You can watch these video clips where they explain in more detail that while the German Tanks were exactly what you would expect from german engeneering, their cost and manufacturing time were just too high to fight in an all out war that lasted for 5 years.
The Panzer IV:
There is no "Best tank", there is the more suitable tank and army. While the Panzer and the German war machine were probably the more suitable Army for short engagements in relatively small areas like Poland, France, the Netherlands and Belgium, The T-34, the Red Army and the Russian People were more suitable for an attrition war in the largest country in the world during one of the harshest winters of that decade.
Many of the sources are Wikipedia, but only because they do such a good job, of summing all the numbers.
I have nothing against Toyota, they make great cars, they were given as an example for a smart and successful operation in contrast to the unsuccessful endeavor of the Maibach brand.