Controversial opinions on metal

Overkill should have been in the Big Four before Anthrax.

They're about equally deserving, both being bands that were among the fastest of the non-innovators to jump on the bandwagon. In a shoulda-coulda-woulda scenario, Exodus and Watchtower deserved it more.
 
There's no way Sepultura would ever find themselves opening a stadium concert with Antichrist in 1987. They lacked accessibility early on, and their straight-up thrash is derivative, crap, and late-coming much like most of Skolnick-era Testament.
 
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The New Order is melodic guitar introduction metal with some thrash influences. The Aerosmith cover is easily the riffiest and most enjoyable SONG (if there's more interlude than song, it's not really a song anymore) on the album.

EDIT: And Feel the Fire owns that album.