I don't have just one "fave." So my list is a little long.
Aly & AJ - Potential Breakup Song (last night, actually!

Ironically on a "Pop Hits" radio)
Hilary Duff - Wake Up (three days ago

on a Hot AC station)
Katy Perry - Teenage Dream (just a few hours ago)
Avril Lavigne - Fall to Pieces (about a week ago)
Natasha Bedingfield - Touch (about two days ago, again on a "Pop Hits" station)
Kelly Clarkson - Already Gone (this morning)
The Veronicas - Untouched (about a month ago)
P!nk - Please Don't Leave Me (about five days ago)
Rihanna - Rude Boy (two days ago - Yeah, I have yet to hear OG on the radio.

)
JoJo - Too Little Too Late (about four days ago)
Miley Cyrus - When I Look At You (last night on an AC station)
Ashley Tisdale - It's Alright, It's OK (a few months ago on a hot AC station - was really shocked they played it)
Ke$ha - Take It Off (yesterday)
Gwen Stefani - The Sweet Escape (this morning)
Black Eyed Peas - I Gotta Feeling (two days ago)
Taylor Swift - Mine (this afternoon)
Miranda Cosgrove - Kissin U (about a week ago)
Fergie - Big Girls Don't Cry (about six days ago)