I think that Kurt Cobain, while not as technically gifted as the others, certainly had the biggest impact on the music out of the others on the list, and everyone else in the early 90s.  Being a GNR fan, I feel that we tend to overstate Axl's influence and abilities as a musician.  Sure, he had his highs and certainly impacted the music scene in the late 80s, but being continually surrounded by controversy and striving for perfection may have limited or shattered whatever legendary status he could have potentially reached.