The concept of an objectively "most attractive" skin tone is subjective and varies greatly depending on personal preferences, cultural influences, and even geographic location. However, studies have shown some interesting trends.
A study by University of Missouri-Columbia researcher Cynthia Frisby found that people perceive a light brown skin tone to be more physically attractive than a pale or dark skin tone. This suggests that a slightly tanned complexion may be considered more appealing by a general population.
However, other research, such as a survey conducted by Boston Magazine, indicates that a medium/olive skin tone is most frequently considered attractive by men.
Furthermore, online discussions like those found on Quora highlight a wide range of opinions. Some individuals favor very fair/light skin with a creamy, dewy appearance, while others find caramel to dusky skin tones most attractive.
Ultimately, beauty is in the eye of the beholder, and the most attractive skin tone is the one that appeals to the individual.