GNR all day long over Nirvana... Both bands were very good, but I gotta go with GNR simply for the musicianship they displayed. They were more diverse, and lets face it Slash is a ****ing beast on the guitar. One must only listen to November Rain to see that they were not to be ****ed with!
I agree with old dude that the Doors are bad ass.... They are indeed one of the best, but the best rock group of all time is Led Zep.
No questions asked... Just let the Led out *****es!