I'd probably suggest that there are better vocalists out there in Metal, however I'll stick to your list as this is just a bit of fun.
Out of those I have only seen 2 of them live and that's Metallica and Soulfly, I've seen Soulfly twice, the first time, flipping brilliant, last time, which only a couple of weeks ago they didn't put on a great show.
But for the sake of argument, I'm going to say:
Max Cavalera
If I could pick one not on the list, I might go for:
Tomas Lindberg - At the Gates
A band influential for the gothenburg sound used by bands today (like In Flames and Dark Tranquility) - they're no longer together (except this year they've been doing a come back tour over Europe, which I managed to catch their only UK gig) and members still have a music career in bands like Soilwork and The Haunted (currently listening).
You sir have the moral ambivalence of a mutated shrimp!