Blitz is a solid thrash metal vocalist, but there's not much use for his vocals otherwise IMO. That being said, I always thought he'd fit into Megadeth if Megadave ever stopped singing.
Neil Fallon is a solid rock vocalist. Clutch is a cool band too. However, I don't think he's a particularly great vocalist. Musician? Sure. Vocalist? Nah. 3rd best in this group.
No one commented on Thebon at all... One of my favorite BM vocalists, as he can do pretty much any vocal style, as showcased on the song I posted. High screams, low grunts, chanting cleans... He had it all. Shame he got kicked out of KoK and then never did anything of note again.
Tomi Joutsen is the clear winner here. Sings in the best band out of all these singers, has great variety in how he sings cleans and growls. Pretty much the perfect modern vocalist IMO.