The appearance of a virtual avatar significantly influences its perceived appropriateness and the user’s experience, particularly in healthcare applications. This study analyzed interactions with six avatars of varying characteristics in a patient-reported outcome measures (PROMs) application to investigate correlations between avatar ratings and user preferences. Forty-seven participants completed a healthcare survey involving 30 PROMIS items (Global Health and Physical Function) and then rated the avatars on warmth, competence, attractiveness, and human-likeness, as well as their willingness to share personal data. The results showed that competence was the most critical factor in avatar selection, while human-likeness had minimal impact on health data disclosure. Gender did not significantly affect the ratings, but clothing style played a key role, with male avatars in professional attire rated higher in competence due to gender-stereotypical expectations. In contrast, professional female avatars were rated lower in warmth and attractiveness. These findings underline the importance of thoughtful avatar design in healthcare applications to enhance user experience and engagement.