Not people in America trying to tell people who are OBVIOUSLY IN OTHER COUNTRIES that Christina's Spanish songs didn't make impact in THEIR OWN COUNTRIES
Anyway, I'm from the US and I don't know.
Genie In A Bottle, What A Girl Wants and Come On Over are 90's CLASSICS.
And Beautiful is more memorable, inspirational and iconic than anything Beyonce has in her discography.
But Single Ladies, Irreplaceable and Crazy In Love....
But then the question is more MEMORABLE not more ICONIC.
In which case Beyonce has my vote, because I think she has more hits than Christina in general.