Anything by Martin Middlebrook; any of his several books about the bombing raids over Germany will be superb.
Anything by Gerald Astor; especially, "The Mighty Eighth."
Anything by Eric Bergerud; especially, "Fire in the Sky" about the Pacific air campaign.
Rick Atkins is starting to look pretty good.
All of the above are written by solid historians with plenty of literary integrity. They deal with whole campaigns, but are filled with individual stories and the awesome, unexpected kind of details of combat experience that you just won't find anywhere else.
And yes, "An Ace of the Eighth" is excellent.
Best first hand accounts by infantry men? "Roll Me Over" and, the most horrifying account of ground combat: "The Forgotten Soldier" by Guy Sajer.
"Flyboys" was pretty insubstantial. A small story about atrocities, puffed up in length to fill a book-length volume.
There's more.
regards, Airman T. E. Shaw