Or, more precisely, between June 22th 1941 (Axis attack on Soviet Union) and Sept 3rd 1943 (capitulation of Italy). Only the in-service bombers of the specified era. Looking for the best mix of bomb load and accuracy, range, survivability, handling, engine-out abilities etc. If the bomber can be easily series produced is also a plus. Future capabilities don't factor here, just the current ones within the specified time.