B26 for me, a widely used medium height bomber.
Used in Europe, the Med and the Pacific
the B-26 stated by the 9th Air Force as having the lowest loss rate in the European Theatre of Operations at less than 0.5%
By the end of World War II, it had flown more than 110,000 sorties and had dropped 150,000 tons (136,078 tonnes) of bombs, and had been used in combat by British, Free French and South African forces in addition to U.S. units. In 1945, when B-26 production was halted, 5,266 had been built.
http://en.wikipedia.org/wiki/Martin_B-26_Marauder