My vote goes (again) to the 'underdog' in this group: Megadeth!
Reasoning: since the singer/founder/gitarist of Megadeth, Dave Mustain was the former gitarist of Metallica and got kicked out, he prooved to his former bandmembers that he could live up to his promiss that he woud make it on his own and he stuck to the bands original genre, metal. As where Metallica mellowed down through the years...
This makes the stats as follows:
Metallica-3
Megadeth-2
Anthrax-0
Slayer-0
Anyone care to challenge? :)