Personally... I would say Guns + Roses is not classic rock. Classic 80s, yes. Metallica is definitely NOT classic Rock... whether they are rock or metal is up for debate ;)

Best:

Beatles, hands down (no other rock group has been as influential, the talent is just icing)

My favorites:

Beatles, CCR, 3 Dog Night, Rolling Stones

I kind of tend toward the Folk-Rock styles (Simon + Garfunkle, CCR, etc)