How can you guys pick just one song?
My favorite song, and it's hard to pick it out because the whole album flows from one song into the next, is "I Can't Feel Nothin'" by Captain Beyond on the album of the same name. Nothing but excellent riff after riff, interspersed with some tastful solos. IMHO that whole album still rocks even after 22 years. It's all about the guitar.
I also like "Topaz" by Journey. Shows Neal Schon at his finest. Quiet, tasteful, but also aggressive and loud. Starts off soft, builds to a wild fevers pitch, then becomes soft again. And best of all, no lyrics to get in the way!;)
