Just to pick up a couple of points.
Cromwell, Churchill etc; had riveted steel! One hit with any large calibre weapon and the rivets pulled, they then became missiles shooting around the inside of the vehicle, ergo: shredded crew.
Sherman vs 88mm; In the last year of the war the Poms equipped some of their M4s with their 17 pounder high velocity gun, and they could and did take on any comers, the L7 105mm weapon of the all the free world's MBT until ten years ago were based on this weapon.
T34; had a cast turret and other parts of the hull were cast and then welded. Better all together than the German welded plates.
Just for interest, the first tank with cast turret to be deployed against the Hun was the French Char B! The first all cast tank, hull and turret was the Australian Sentinel (
Sentinel tank - Wikipedia, the free encyclopedia ) which never fired a shot in anger, but at the end of its development cycle was much akin to the A43 of the Poms which became the Centurion. And as I've mentioned before, in spite of the Cent being powered by petrol, in service with the Israelis, across all their wars, has never "brewed up."
So I guess the lesson is that the basis of tank design is the compromise between; firepower, protection and mobility. It is the designers dilemma to balance this three legged horse.