Good topic... I have so many favorite songs/artists, but these are songs that have really been speaking to my life lately...
Rock/Alt:
We Never Change ~ Coldplay
Hip Hop:
Shooter ~ Lil' Wayne w/ Robin Thicke
R&B:
Booty ~ Erykah Badu
Pop:
Well, Well ~ Nelly Furtado
Old-School:
We're A Winner ~ The Impressions
Jazz:
Sophisticated Lady ~ Ella Fitzgerald