LFN is way too overhated. It's one of the most interesting party songs of 2010-2011, it's not just like "yeah hands in the air in the club", it actually has a chorus (and verses) which take you on a journey of a crazy Friday night. It's really well thought out.
But really, Birthday only has so many plays because I didn't start using last.fm until Sep '13 and I play*****d Birthday during its single run to try and get into it more.
I Kissed A Girl vs CG
Hot N Cold vs Teenage Dream Firework vs Part Of Me E.T. vs Last Friday Night (T.G.I.F.)
The One That Got Away vs Wide Awake Dark Horse vs Roar