M4 Sherman, Allied basic tank, next to T-34 in Museum of Polish Army.
Looking at those two, advantages of T-34 are obvious. 1. Sherman has no sloped armour on its sides, therefore it's vurnerable to anti-tank weapon; 2. Sherman is higher and thus harder to hide for example in forrest terrain; 3. Sherman's machine gun is partially blocked by equipment holders; 4. Sherman's suspension is more complicated, making it harder to repair; 5. the front is bolted, so weaker and wouldn't be able to withstand the impact of shell.