I nominate
Jan Olieslagers as the worst ace. He flew 491 sorties and engaged in 97 dogfights, yet his 5 qualifying victories took 2 years and 8 months to achieve. His first was on 12 September 1915, his fifth was on 3 May 1918. Thereafter he had only one further victory, 2 weeks later, on 19 May 1918.
Er, mind you he did survive the war, which is more than many of his betters did.
You can have the concept of a "worst ace" without denigrating someone who risked his life in aerial combat.
Vin