The worst death metal album I've heard? Probably Necrophagist's Epitaph. This band fails so much at death that it's hard to believe they're not just a really shitty parody band. They literally distilled everything wrong with death metal into a disgusting soup of overproduction and flowery guitar solos. It's just mindless technicality without any sort of message, ideology, spirit, soul, "it", whatever the fuck you call it. They don't have it. They can solo up and down the neck like Yngwie all day long, but don't go to this band for any kind of actual artistry. This band is fake.
Death metal didn't start out as a vehicle for technical displays; rather, good "tech death" bands like Atheist, Cynic, Demilich, and Gorguts use technicality as a means to an end. That end being, of course, a communication of the inevitability of mortality, the uselessness of the modern concept of individualism, and the foolishness of ideologies that promote a worldview contrary to reality. That is what death metal is about, whether one goes the way of Cynic in extolling a transcendental sense of oneness with the rest of the world, or one takes the Autopsy approach of glorifying death in all its forms as necessary, or one chooses the blasphemous route of Incantation and Immolation. What the hell is Necrophagist about? "Look at me! I can play fast! Goddammit, look at me! I deserve your attention!"
In short, fuck off Necrophagist.