I recall an interview with a German fighter pilot in the 'World at War', where he'd tell new pilots that the American bomber crew would start shooting at too long of a range to be effective and to close their eyes if the tracers bothered them. Later on in the conversation he paused when talking about the Mustang, saying that they didn't have anything as good.
The Spitfire was evidently the only fighter in production at the start of the war and the end of the war. The company, designer and plane are a remarkable story.