I was always partial to this one in terms of range/mastery.
Everyone knows he's capable of belting it out
(Black Hole Sun, Say Hello to Heaven, etc etc) , but he shows a lot of texturing and restraint while still commanding a huge range... and belting it out a few times for good measure.
EDIT: I'm not trying to say Cornell is undisputed #1 in terms of vocals... Freddie Mercury, Whitney Houston, Mike Patton, there's a healthy number of all time greats. I've just always regarded Chris Cornell very highly.