Here's why we can't say for sure:
* Personal Preferences Vary: Each member of Queen (Freddie Mercury, Brian May, John Deacon, and Roger Taylor) would have their own taste in music and favorite singers.
* Influences from Many: Queen was influenced by a wide range of artists, from opera singers like Luciano Pavarotti to rock stars like Little Richard.
* Respect for Talent: They likely admired many singers for their different skills and styles.
Instead of a single favorite, we can say Queen was clearly inspired by many incredible vocalists. Freddie Mercury himself was a master of vocal techniques and paid homage to various singers in his own work.
Perhaps the best way to understand Queen's musical influences is to listen to their diverse music and explore the artists they covered or cited as inspirations!