Determining the best musician of all time is inherently subjective, as it depends heavily on personal tastes, cultural significance, and the specific criteria one prioritizes. Many lists and polls often reference Wolfgang Amadeus Mozart, Ludwig van Beethoven, or Johann Sebastian Bach from the classical period, or The Beatles and Michael Jackson in more contemporary settings, due to their extensive influence, innovation, and popularity. Recognizing one as the "best" inevitably discounts the monumental contributions of countless other musicians across various genres and eras.

The ambiguity of the original prompt resides in its lack of defined criteria for what makes a musician the "best." To make the question more objective, specific criteria would need to be established. For instance, one could consider the breadth and innovation of a musician's work, their influence on others in the field, technical skill, and versatility. Additionally, metrics such as record sales, number of awards (e.g., Grammys), and critical acclaim could be quantitatively measured. Each of these criteria could tip the scales in favor of different musicians, highlighting the multifaceted nature of musical excellence and the challenge in naming a singular "best" musician.