A lot of the "Cobain or not cos he's dead" things are why I generally go with Eddie Vedder. He's been able to keep Pearl Jam, a band that sprung up in the exact same scene as Nirvana (they knew each other when they were all just the local bands going to each others gigs) but have actually continued to make music and score billboard hits 20 years later.
There's a decent amount of depth and variation to what they make/he writes. He's perfectly at home playing on his own to an sized crowd or being frontman for a pretty awesome setup.
I'd call Dave Grohl as second pick for similar reasons.
Do agree with the John Williams and Tom Morello choices tho. Morello was a bit about being able to do silly things with a guitar but it's a style that's totally definitive, engaging, unique and "his".
I DID say at the start of the thread it's going be rather varied answers which is a nod at, yup, it's subjective