1. The Beatles
2. Led Zeppelin
3. Radiohead
4. Pink Floyd
5. The White Stripes (yeah, that's right)

I could have mentioned Hendrix, the Who, the Clash, Wire, etc... but my taste was formed this decade, so consequently, the White Stripes hold a special place.

Also, eggtweedyegg:

if you don't consider Radiohead a rock band what DO you consider them? An art band?