A few new-ish ones I can recommend, the first two being surveys of recently-discovered source material, the third a valuable 'alternate narrative,' as the kids say:
The Deserters: A Hidden History of World War II by Charles Glass; Penguin, 2013. "A survey of the 150,000 American and British known to have deserted in the European Theater."
Soldiers: German POWs on Fighting, Killing, and Dying by Sonke Neitzel and Harald Weltzer; Knopf, 2012. "...a unique and profoundly important window into the true mentality of the soldiers in the Wehrmacht, the Luftwaffe, the German navy, and the military in general."
The Second World War: A Marxist History by Chris Bambery; Pluto Press, 2014. "A comprehensive and detailed alternate history of the origins, cause and aftermath of World War II."
Cheerful stuff.