Out of those 48,000 T-34 losses, how many were actually destroyed by the Germans in battle, as opposed to simply being abandoned by their crews when they got surrounded, or ran out of fuel, or broke down? If you take those numbers out of consideration and only consider combat losses, I suspect the ratio to the Sherman would be a lot closer.
'Jane's Tanks of WW2' (an excellent book) has this to say about the T-34:
The introduction of the T-34/85 gave the Soviet Union what it needed, a tank with a lethal gun, good armour protection and excellent mobility. Reliability, although improved near the end of the war, remained a shortcoming, but the huge numbers produced meant that tanks could be replaced when the engines burned out or the transmissions failed.
In other words, the Sherman was designed to be easy to repair if it broke down. The Soviets simply said, "Hey-ho, this T-34 is broken, give me another one".
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Regarding the Sherman M4, one important fact to consider is that US armoured vehicle doctrine before they entered WW2 was rather special. They believed that the purpose of a tank was to support infantry attacks and spearhead offensives - not to fight enemy tanks. That was the job of specialised, dedicated 'tank destroyer' units using vehicles like the M10 Wolverine or M18 Hellcat - which were very fast but thinly armoured because they were supposed to be used from ambush.
As a result of this doctrine, the Sherman was deliberately designed with a gun that wasn't very good at armour-piercing, but could fire large quantities of high explosive shells against soft targets. The Army authorities, such as General McNair, were very pleased with this policy - until American tanks actually met German tanks in large-scale ground combat after D-Day, and they realised they'd made a horrible mistake. The Sherman Firefly was a British attempt at a stopgap emergency fix, which involved cutting a hole in the back of the turret (!) to make room for a much larger 17-pdr gun.
The British went on to design the Comet as a purpose-made medium tank designed to use the 17-pdr; the Americans, unable to find an effective replacement for the Sherman in time, instead prioritised production of the M26 Pershing heavy tank instead.
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As for the Germans, the statement that, say, the Panzer IV G was better than the original-version T-34 seems to be missing the point. The T-34 was designed before the war and entered service in 1940; the Panzer IV G was designed in 1942 - as a direct result of the Germans seeing the T-34 in action and thinking, "Crap, we need to come up with something to match that, quick!"
Of course the later design, made with all the benefits of hindsight, is going to be better than the revolutionary and ground-breaking original version. And so the reputation of the T-34 comes, I think, from the fact that it came first, and its combination of sloped armour, wide tracks, and powerful gun couldn't be matched at the time. The host of imitators that copied it aren't more famous even if some of them were technically better.