I feel like outside of Europe, noone remembers Hung Up
Well, and I think you're dead wrong. It was a mammoth single basically everywhere , including (besides Europe) Australasia and Latin America + Canada . So, the only country where it did not smash was in the US
And are we really trying to use the argument that Hung Up may possibly be remembered (it won't and argueably already isn't imo) , when WE KNOW Believe is already remembered and used in film, television, and pop culture 16 years later currently
I'm gonna have to go with Believe. Hung Up isn't even Madonna's biggest hit, so I don't think it's a fair comparison in that respect. Plus, Believe is the song that literally invented auto-tune and brought it to the mainstream. Not to mention that, if I'm correct, Cher is the oldest woman to receive a #1 on the Hot 100, through Believe. It's the definition of a legendary song.