Hans-Joachim "Jochen" Marseille. The Star of Africa.
His flying skills and marksmanship was second to none. Another flying ace and later General of the German fighter force, whom himself would be in the running for "best fighter pilot ever" had this to say about Marseilles:
"Marseille was the unrivaled virtuoso among the fighter pilots of World War 2. His achievements had previously been regarded as impossible and they were never excelled by anyone after his death."
- Adolf GallandHe was a killer in the air, but he also had a heart, in a letter to his mom he wrote: "Today I shot down my first opponent. It does not sit well with me. I keep thinking how the mother of this young man must feel when she gets the news of her son's death. And I am to blame for this death. I am sad, instead of being happy about the first victory."
He claimed 158 enemy aircraft destroyed in little more than two years until his death. All against the Western Allies. 17 kills in one day. Unlike most other 100+ German aces Marseilles was never shot down and remains undefeated. His death came in the form of an engine malfunction and he did not survive the bail out.
What makes a great fighter pilot is perhaps also his popularity, Marseilles was an international icon in his time, much like the Red Baron in the previous war. He was every bit the ladies man in real life that Tom Cruise tried to be on-screen.
Johannes Steinhoff, another German ace who was Marseilles' commander at one time said this about him: "Marseille was extremely handsome. He was a very gifted pilot, but he was unreliable. He had girlfriends everywhere, and they kept him so busy that he was sometimes so worn out that he had to be grounded. His sometime irresponsible way of conducting his duties was the main reason I fired him. But he had irresistible charm."
And when he died his whole fighter wing (JG27) had to be withdrawn from combat for about a month because of the impact Marseille's death had on morale.
I don't know of anyone who can top that.