I'm going with The Beatles and Jimi Hendrix.
I picked the Beatles as my #1 because.....well, listen to Magical Mystery Tour, Revolver, The White Album, Help! and Let It be, and tell me they're not greater than CCR (even though CCR is great).
And I got Jimi and the Experience as my #2 because they singlehandedly defined the sound of psychadelic rock. Purple Haze is the definitive song of the late 60's.
The next bracket should be all prog (Yes!, Kansas, Rush, etc.), and then the next all solo artists (Elvis Costello, Bob Dylan, Neil Young, Ted Nugent, etc.)
And pyro, not all rap is crap. You need to listen to some Edan and MF Doom and then take back your words.