If we are talking pop/rock music – the first thing I notice is – do they like what they play and sing? If I think so I began to listen, and for me the singer is quite important. Take Emmelou Harris, every song she sings, she makes her own song, so even this small country songs I can enjoy.
Ella Fitzgerald is a fantastic singer, I enjoy much of her interprets. But is she a singer? In a way she is the best saxophone singer/player I know, so she is more a member of the band. Ellington called her, when he need this sound in his orchestra, and he get what he wanted.
You remember the 3 tenors in Rome? Well great songs and music, but with no joy - at least for me. It was money in the pocket, no more than that.
Music matters and need love and affection, as the wonderful Joan Armatrading sing. So for me the statement “Love and Affection” is important in every music making.