No way you get out of this one without some clear-cut examples. Cobain's lyrics were deep, "Something in the Way" was very personal and direct. Layne Staley never got that poignant, imo (and yes, I'm even including "Junkhead")
In fact, the best thing Layne Staley ever did was probably the Mad Season record.
The title of this thread is ridiculous, too. Mia Zapata's death had a bigger impact on grunge than Layne Staley's (as someone else pointed out, Alice in Chains had been done for a while by the time Staley died). Still does, actually...
Pearl Jam was/is/always will be complete garbage, definitely agree with that.
Soundgarden were opportunists who started out as a hair-metal band in the late 80's (go check the album "Ultramega OK" and try not to laugh, even the biggest Soundgarden fans can't argue that), and then realized there was a different lane brewing early on and got into the whole Seattle grunge sound with "Badmotorfinger" (which is one of the best albums ever in the grunge genre)