I vote the DB-3 first. More prominent level bomber for the Soviets in WWII, carried 5500 lbs of ord. Then, the IL-4 would be my second best.
The Tu-2 and even the Pe-2 would not be bad, but the DB-3 would be best. It was to the Soviets as the B17 was to the US. The IL-4 would be to the Soviets as the B24 would be to the US.