I had seen Gorme perform it on a late night talk show before Mame opened on Broadway, and she knocked it out of the park, especially when she did the line "and not enough of me". The way she sang that line gave me goose bumps.
Lansbury, however, was even more visceral and really angry at herself -- her hair was in the bob she had in the show and I think she was costumed in a sleek, short dress that was so classy and elegant. Her rendition (unlike Gorme's) included the "Where's that boy with the bugle?" introductory verse and that final line "if that boy with the bugle walked into my life (pause) today. Magnificent!