The Fame and 1989 are really close in US.
They're both 6x Platinum in TEA, and it's obvious 1989 will pass it, but you have to factor in she was a new artists versus an artist who has the biggest fanbase of any muscician on the planet.
Poker Face and Just Dance were also bigger singles than SIO + BS. But Style and LoveGame are both forgotten flukes of the era, while Bad Blood > Paparazzi in terms of success.