Using a fuzzy approach, this paper aims to identify the main factors influencing auditor quality and rank them according to their relevance. For this purpose, a study was conducted with a sample of 12 experts, issued from Big 4 and non-Big 4 firms. The results show the existence of multiple attributes and traits of characteristics that notably influence auditor quality, such as professional skepticism (Gi = 4.519), due professional care (Gi = 4.491), accountability (Gi = 4.384), independence (Gi = 4.069), and integrity (Gi = 4.043). However, technical knowledge and motivation were found to have a relatively minor impact due to their Gi being below the defuzzification threshold (α = 3.50) and were therefore rejected. In terms of value, this study stands out for its integration of an innovative methodology that has been little applied in the field of auditing, and even less so in the Moroccan context. At the same time, the analysis of auditor attributes is necessary to assess how they might affect the quality of auditing services, offering thus new perspectives on this topic.