Wow! There are some really dumb answers on this one. A person who does not kill themselves is a stronger person? How about a little compassion for those who deal with severe depression and drug addiction?
Claiming that you're not a FooFighters fan, but you're a Dave Grohl fan? That's idiotic! Dave Grohl is The Foo Fighters. The debut album was recorded entirely by Grohl, by himself. He named himself The Foo Fighters to hide the fact that he wrote all the lyrics and music, played all the instruments, produced and recorded it by himself. The Foo Fighters band was formed after the fact to tour the music that Grohl created and recorded on his own.
The notion that taking heroin makes you a better artist is just plain stupid. The artists whom you mentioned all suffered from depression, insecurity, and struggles with their emotions and anxiety. Drug abuse was a symptom of their troubles, not a way to channel their talents. Their music was an outlet and a release for all those pent up feelings and emotions. They played great in spite of their drug use, not because of it. They wrote and played great songs because they were tortured souls, with incredible musical talent. They abused drugs because they were tortured souls. The drug use had nothing to do with improving or releasing their talents. It was simply a way to cope with all the crap that was going on inside their heads. But, their talent was great enough to outshine and overcome the drug abuse, most of the time. Any former addict will tell you that they played much better sober than when they were wasted all the time. They just didn't realize until they got clean again.
Cobain and Grohl are both great, but I have to give Grohl the edge, because he is a perfectionist, who did it all on his debut album. He was a one man show, making the entire record from scratch, by himself and that takes incredible talent.