I Kissed a Girl still slays me to my very soul. The lyrics, the vocals, the beat, the production, the guitar (especially on her recent live performances), give me no mercy. Hell, even the video makes a good go at it with its hidden message. 11/10, best lead single I can think of.
I demand y'all stop taking about that song as it forces me to sit with it on repeat all night.
Oh, and someone mentioned Ryan Tedder a few pages ago - she worked with him for Teenage Dream and created "the new Hot n Cold" and some "roller skate party" tracks, apparently was trash tho.