Recently I read a Yahoo article on how from 50 years on Mariah will be probably remembered AIWFCIY despite having other hits like Brenda Lee.
WBT is still popular in US so that may be in line. But it changes from country to country as Liron said. Here it is My All and Without You - given we dont celebrate christmas AIWFCIY is not as popular.
However i think ABMB could have been more popular if she worked on it a bit more instead of singing MIH for the gazillionth time in specials, shows etc.