Firework for sure in the US. Theyre equal in sales and should gain a big lead on PF with New Years and the next 4th of July. Those two holidays are also the reason its bigger.
Didn't it take Firework half the time it took Poker Face to go Diamond? Anyways iTunes US: Firework 1006, Poker Face N/A. Plus Poker Face has less views than TIHWD on vevo. So I'm gonna go with the SuperBowl closer