The question of who the "best" musician of all time is highly subjective and depends on personal taste, cultural context, and the criteria one uses to define "best." If we consider a musician who has had a profound and lasting impact on music across genres and generations, one could argue that The Beatles, particularly John Lennon or Paul McCartney, or perhaps Bob Dylan, have made significant contributions. The Beatles revolutionized popular music with their innovative songwriting, production techniques, and influence on various musical styles, while Dylan transformed the role of the singer-songwriter with his poetic lyrics and political activism. However, "best" can also mean technical mastery, commercial success, or cultural influence, and each of these dimensions might lead to different conclusions.

The inherent ambiguity in the original prompt lies in the lack of clear, objective criteria for determining what constitutes the "best" musician. Without specifying whether the term refers to technical skill, artistic innovation, cultural impact, or longevity, the question remains open to wide interpretation. To make the answer more defensible, one would need to establish precise metrics, such as the number of influential works, the degree of innovation introduced, the breadth of musical genres influenced, or even measurable factors like record sales or critical acclaim. Additionally, the time frame for consideration (e.g., only 20th-century musicians or including historical figures) would need to be clearly defined. Ultimately, the question invites debate rather than a singular, definitive response due to its broad and subjective nature.