I didn't know who Judy Garland was. And I can assure a lot of people who are in their 20s or less don't know her either. I am sure it isn't as famous in the rest of the world, once again US is not the whole world. I have never watched that movie. Madonna is well known all around the globe from kids to grandparents so the answer is obvious.
at certain stanbase replies. I am sure if this were a Judy Garland vs certain pop-star. Their votes would be different. So transparent.