If we're talking about being revolutionary in music, no one changed music more than Kurt. Not to say that Hendrix didn't change anything, but look at what kind of music was in the mainstream pre-Nirvana and after. It completely changed. My favorite band before then, GnR was practically kicked out the door along with other bands.
The same didn't happen with hendrix; jam bands and folk singers still owned a bigger chunk of the music business pie.
Now if you look at the longest lasting change in music, Hendrix wins hands down. Without hendrix you wouldn't have bands like Led Zeppelin, Metallica and so on. Hendrix is the godfather of heavy metal, and I think everyone knows heavy metal has lasted alot longer than grunge.
Nirvana never created a genre (if you call grudge a genre), they were a punk band who just happened to be good (if you know anything about punk, the music isn't supposed to be good) and made it pop enough for mainstream. Listen to there stuff pre-smells like teen spirit, its punk.
P.S. I mean good as in the studio, not live. Nirvana with a few exceptions were horrible live. One of those exceptions in my opinion is the unplugged in NY. Not just the music but the atmosphere (that goes so far the breathe itself into the recording as well) is just amazing to actually hear.
The problem I think is they are from two completely ( and I mean completely) different generations. Every so on there are guys who change the way we view music, as in this example. D. Ellington, The Beatles, and so on. Both Hendrix and Nirvana are just those guys who did just that.
"My whole life is a dark room...ONE BIG DARK ROOM" - a.f.i.