[Rizla]

If you want something from the German side:

Willi Heinrich, The Cracks of Doom and The Cross of Iron (the movie was based on it). He was really in the war and survived the retreat to Germany.

The Forgotten Soldier, Guy Sajer (according to the author, not fiction, but been accused that it's fiction. Great book, in any case.)

Also The Last Enemy, by Richard Hillary, which is an autobiography and freely available on the net.

One of Our Bombers is Missing, by Dan Brennan, deserves a mention. He was a American who volunteered for the RAF early in the war. A forgotten author, and the best book I've read from the perspective of the bombers.