It's a tough one between Rage Against the Machine and Led Zeppelin. I love Tom Morello's guitar work and the amazing lyrics of Rage. But Led Zeppelin is so darn great. I don't know if I can make a decision.
This really depends for me. Do you mean best sound? Best lyrics? Best writing? Best ideas? Best looking? Etc. I have so much music going on in my head at any given time that it's now hard for me to tell what song is on the radio or my iPod or whatever. Try 2k+ songs. :P
Absolutly KISS! Today maby not as good as before. Theese days there is Thommy Taylor and Eric Singer in the way for Ace Frehley and Eric Carr/Peter Criss (Eric Carr is dead). But the old KISS is always KISS!