Saying that Jimi hendrix made better songs is complete ********! Noone can judge which songs are super and not, its a matter of taste and therefore an individual thing.
Hendrix created music that was difficult to play and that was highly 'advanced' - Cobaine created music with atmosphere
You will be able to see both elements in modern music but for the recolutionary part it all depends on the person affected - they affected different groups and I find it hard to compare inpact when it is spread over a wide area.
cheers