The question of who the "best musician of all time" is inherently subjective, as musical excellence is shaped by cultural, historical, and personal contexts. However, if forced to name one figure, **Beyoncé** often emerges as a contender due to her unparalleled influence on pop and R&B, her genre-defying artistry, and her impact on contemporary music and culture. Others might argue for **Jimi Hendrix** for his groundbreaking guitar innovations, **Beethoven** for his foundational role in classical music, or **The Beatles** for their revolutionary contributions to popular music. Ultimately, the answer depends on which criteria—technical skill, cultural impact, innovation, or commercial success—are prioritized.  

The original prompt is ambiguous because "best" lacks clear, objective standards. To make the question more defensible, specific criteria must be defined, such as: 1) **Influence on subsequent musicians or genres**, 2) **Technical mastery and innovation**, 3) **Cultural or historical significance**, 4) **Commercial success and reach**, or 5) **Critical acclaim and awards**. Without these parameters, the question remains a matter of personal taste, as different individuals and cultures value distinct qualities in music. For example, a classical purist might prioritize Beethoven’s complexity, while a fan of modern pop might emphasize Beyoncé’s cultural resonance. Defining criteria would transform the question into a measurable debate rather than a subjective opinion.