no way i could ever pick one, but the first couple that come to mind are...
bohemian rhapsody - queen
piana man - billy joel
lost symphonies - saosin
about 30 beatles songs
all along the watchtower - jimi hendrix
firefly - saves the day
fortunate son - ccr
missed the boat - modest mouse
come monday - jimmy buffet
free falling - tom petty
brain damage/comfortably numb/atom heart mother suite - pink floyd
it's hard for me to say much current music can be a favorite song since i can't compare it to the stuff i grew up listening to
edit: can't believe i forgot pink floyd, wow.