**Answer:**  
Determining the "best musician of all time" is inherently subjective, but one frequently cited figure is Ludwig van Beethoven. His transformative compositions bridged the Classical and Romantic eras, showcasing unparalleled innovation, emotional depth, and technical mastery. Despite losing his hearing, he created groundbreaking works like his Ninth Symphony and "Hammerklavier" Sonata, which continue to influence musicians across genres. Others might argue for artists like The Beatles, whose cultural impact reshaped modern music, or Jimi Hendrix, whose guitar virtuosity redefined rock. Ultimately, the answer depends on the criteria prioritized.

**Analysis of Ambiguity:**  
The prompt’s ambiguity lies in the undefined term "best," which can refer to technical skill, creativity, cultural influence, commercial success, longevity, or genre-specific achievements. For a defensible answer, criteria must be explicitly outlined. For instance, if the goal is to measure *impact on music evolution*, one might analyze how a musician’s work altered compositional techniques or inspired subsequent genres. If prioritizing *popularity*, metrics like record sales (e.g., Elvis Presley or The Beatles) or streaming data (e.g., Drake) would apply. *Critical acclaim* could rely on awards or peer recognition, while *technical mastery* might favor classical virtuosos or jazz innovators. Additionally, defining the scope—solo artists vs. bands, Western vs. global traditions—matters. Without such parameters, the question remains a matter of personal opinion rather than a factual debate.