For anyone who enjoyed Geoff Wellum's First Light or Pierre Clostermann's The Big Show I can also strongly recommend James Goodson's Tumult in the Clouds, a gripping, brilliantly written account of his war flying Spitfires in an Eagle Squadron then P-47s and P-51s.
For something a bit more recent I'm still a big fan of Robert Prest's F-4 Phantom: A Pilot's Story, about flying Phantoms with the RAF in the seventies.
And in case it didn't get mentioned because it was just too obvious, Chickenhawk, Robert Mason's book about flying Hueys in Vietnam is just about unbeatable.
On the fiction front, it's worth looking out for Mike Lunnon-Wood's Long Reach and King's Shilling, military thrillers about a Guatemalan invasion of Belize and a British intervention in West Africa respectively.