What do you mean by "quality"? A lot of people are not fond of the book.

Well, are you looking for historical fiction or non-fiction?

If you are looking for non-fiction, I would say that John Keegan's The First World War is a solid book that is considered by most, in unison with the easily digestible work by Gerard de Groot titled The First World War as well.

If you are looking for memoirs, I can suggest some that I have heard good things about, but I have never read any of them yet. Some good ones seem to be A French Soldier's War Diary, 1914-1918 by Henri Desagneaux. This has a recollection of Verdun.

There also is Ghosts Have Warm Hands: A Memoir of the Great War, 1916-1919 by Will Bird. That is thought to be one of the better Canadian accounts of the war.

If you are looking at some more specific events, my personal favorite to study about is the mistake that Churchill made with the battle of Gallipoli. It is regarded by churchill as his greatest mistake of his career. A decent book on the events would be Peter Hart's Gallipoli. I believe it is one of the better texts as he uses both turkish and british sources to try to create a better perspective on the events.

If you have any questions about any of the books or would any other suggestions, just reply or PM me. I'll be glad to help!