Oh man, that's a tough one. There's so much amazing music out there. I love rock, both old and new. When it comes to my ABSOLUTE favorites I'd have to say...
New Stuff: Taking Back Sunday, My Chem, Muse, The Format, The Killers, The Strokes, The Honorary Title, Paolo Nutini, The Ropes, The New Pornographers, Regina Spektor... the list goes on
Classic Rock: Elton John! He's probably my favorite ever, along with Cher. Yes, I love, love, LOVE Cher! Also Billy Joel, John Mellencamp, Bruce Springsteen, Steve Miller, Supertramp, Pink Floyd, Zeppelin, Rolling Stones, Aerosmith, The Clash...
There's so much more!