Ringo started and basically popularized the 4/4 beat, while Dave Grohl is decent, not some god prodigy, like Neil Peart or Mike Portnoy, he was up staged by many "grunge" era bands.
I hate Paul as much as I hate warm beer.
Krist is what you call "I'm good for this band, but if i joined another band, I'll degrade them".
Cobain is highly over-rated. His song writings are not even comparable to John Lennon, Pete Townshead, and even fromt there time, Eddie Vedder, Jerry Cantrell, Layne Stayley.
Hell Layne is the best singer that came out of the 90's.
Kurt guitar ability is the only thing is puzzling me. Not a shredder, doesn't really show it live, by playing sloppy like Jimmy Page...I think he does hold back a bit though, but he's still nothin special.