When I had singing lessons, I used to love "Memories". I suspect my singing teacher got fed up of me murdering it, but I enjoyed it!
Also love "Over the Rainbow", the Eva Cassidy version and Nina's Simone's "I wish I knew How it would Feel to be Free".
One afternoon when I visited my Mum, the home had an entertainer who sang "Over the Rainbow" with a Ukele. As he approached the final bars, one of the residents began to sing, in a sweet high voice. Before that, she had only screamed. He slowed down and let her sing the final refrain. We were all in tears.