Holy Jeez, there were so many good games for the old NES and SNES systems it's nearly impossible to narrow down my favorites, but here's my attempt.
NES:
1.Gyruss Stage 1
2.Marble Madness Level 2
3.Nearly every song track from Castlevania 3, but favorite was "Aquarius" and "Dejavu"
4.Double Dragon Theme music and Level 1
5.TMNT (original) underwater Dam music and Mini-boss music
6.Battle Of Olympus all tracks but hands down favorite was Phygria stage.
7.Mega Man 2 all tracks but favs were Metal Man, Crash Man, Flash Man, Quick Man
8.Punch-out theme music
SNES:
1.Castlevania IV First stage
2.Mario Kart Rainbow Road
3.Star Fox Corneria stage
4.Contra Stage 1
5.Super Street Fighter 2 all tracks but favs are Balrog, M.Bison, T.Hawk, Ryu
6.Super Metroid Lower Norfair and Brinstar areas
7.Nearly all music from Zelda: A link to the Past.