Denis Winter's The First of the Few is a study of RFC/RAF fighter pilots of the Great War. Heavily sourced from memoirs; the bibliography is full of good reading.
Ian Sumner's Kings of the Air does a similar study of French airmen, the only one of its kind I've found readily available in English.
Samuel Hynes' The Unsubstantial Air covers American airmen, in US, French and British service. A distinguished professor of Edwardian literature at Princeton, he was also a Midwestern farmboy turned Marine TBF pilot, and he brings all that insight into looking at young men losing their innocence in warflying.
Then there's Oliver Stewart. His book The Clouds Remember is a memoir of the types of planes he flew as a scout pilot and a test pilot.
He wrote The Strategy & Tactics of Air Fighting in 1925, to try and summarize the successful fighting tactics from the war. Reportedly one of the books looked up by RAF pilots in 1940 when they found that the prescribed tactics weren't working.
https://www.scribd.com/document/125476120/The-Strategy-Tactics-of-Air-Fighting-by-Maj-Oliver-Stewart
And then there's his novel--a thinly disguised autobiographical account of his war service. Published under a pseudonym, so he could tell the truth. More on that here:
https://greatwarfiction.wordpress.com/2016/07/07/portrait-of-an-airman-byphilip-arnall/