I heard an amazing fact on a TV show several years back, not sure if it is true:
during WW2 the allies used a wide range of bombers over Europe, including Lancs, B17s Liberators, Marauders, Stirlings, Mitchells, Halifaxes, various Lockheeds and Mosquitos. A huge tonnage was dropped, and 75% of it was dropped by Lancasters!