John Legend Just Can't Pick His Favorite Aretha Franklin Song

John Legend picking a favorite Aretha song is like eating just one potato chip ... it's just impossible.

John was flying solo Thursday night at Craig's in WeHo, when our photog asked if one song from the Queen stood out. Check out John's answer. He probably could have gone even longer.

Aretha's funeral service is being held today, and it's like the Grammy's ... Jennifer Hudson, Ariana Grande, Stevie Wonder, Patti LaBelle, Faith Hill, Fantasia, Chaka Khan and on and on.

Former Prez Bill Clinton will speak.