The running gear was more reliable and easier to repair. T-34 crews had to be careful that small rocks wouldn't get in between the guide teeth and ruin their day. Their diesel engine was less durable then the Wright 9 cylinder radial aircraft engine. Shrapnel punctures the radiator of a T-34 and it'll overheat and stop running eventually. Diesel fuel must be kept free of water and contaminants too.
Some say the Sherman's 75mm gun was more accurate and reliable then the T-34s 76mm. I don't know. The Sherman did have superior optics. Crew comfort was superior in the Sherman as well and the 3 man turret made the tank much more effective in combat then the T-34s 2 man turret. In the T-34 the tank commander was also the gunner! This would explain the more then double loss ratio compared to the Sherman against the German Tiger I. All Shermans had radios to coordinate attacks, I think only the platoon leaders did with the T-34s.
I'll stick with the M4 Sherman. Alright, let's do a match up! Who's got a running M4 or M4A1 and T-34/76 we can borrow? We'll fire paint shells at each other!

BUT! If I had to pick one tank to fight WW2 in it would be the Buick M18 Hellcat! I know, it's not really a tank, it's a motor gun carriage. Despite the open topped turret and light armor not as many were lost compared to the Shermans. Speed is life! While that Tiger is waiting for his turret to swing around you gun the engine, flank him and put a 76mm round in his engine compartment or take an extra second aiming to shoot off one of his sprockets! Then move and shoot again!