I'll have to add to the T-34 discussion but I'll also throw in the KV-1 here.
But first let us focus on the T-34, Heinz Guderian may have said the T-34 to have been superior. However we must consider that like many German soldiers, he was biased in what appeared to be an impenetrable super tank compared to "obsolete" German tanks. As such closer inspection is required.
The T-34 suffers from poor Fire Control Effect or FCE. FCE is everything from identifying the target, acquiring the target, and shoot the target. This is not just due to poor optics on the gunner sights, this also includes the ability of the driver, commander, etc, the entire tank as a whole because everyone should be able to identify targets for the gunner and call them out. Because of this poor FCE many T-34s were destroyed by so called "obsolete tanks" even after the major operational losses of 1941 and we start getting into majority combat losses in 1942. The Soviets gambled on a superior gun and superior armor. However, the Germans had the correct idea in emphasizing FCE over armor. After all if you hit the enemy first, you don't have to worry about the enemy. But also if you get hit first, you ensure that the enemy is hit more often.
Given the increasing firepower of ATGs and tank cannons increasing armor was a futile effort. This is vindicated by post war tank design with a large amount of the tank dedicated to FCE. Hence it is strange to tout the KV-1 as being superior on armor alone. After all, armor means nothing if the tank is destroyed in ambush by ATGs, close in infantry assaults etc. In fact these are responsible for the majority of tank losses, not tank on tank engagements.
Getting back to the T-34, this poor FCE remained even on the upgraded T-34-85. The result was that no matter how good the soviet crews were in relation to their german counterparts, they could not overcome this fatal design flaw that the T-34 had right up to the end of the war. Also who would call a weapon system that can not achieve better then a 3:1 loss to kill ratio a good weapon system. No one would say this of any German or Western Allied weapon system and the T-34 does not deserve special treatment.
That being said, at the strategic level it was successful. But only because other German armored fighting vehicles were having to be directed against the Western Allies. Remove the Allies and the kill to loss ratio for German AFVs to Soviet AFVs, that is TDs, SPGs, MBTs, etc, is still in the German favor and not only wipes out the entire Soviet AFV production in the war, but also the entire soviet AFV force in operation barbaossa. This is without correcting for no strategic bombing, luftwaffe air superiorty because they are not defending the Reich from bombing, and 10,000 heavy ATGS with full complement of supply.
In short, the superior armor and firepower and cheap mass production abilty of the T-34 is not enough by itself and could not save the Soviets with swarms of T-34s. The T-34 needs help at the strategic level in order to succeed and luckily for the soviets, they had that strategic help.