The sharpest point that I ever heard in the Priest vs. Maiden debate is that Judas Priest are more of a guitarist's band, whereas Iron Maiden are more of a bassist's band. Regardless of which side you fall on, this makes perfect sense. For all of their bombast, Maiden's solos are relatively succinct, and songwriter Steve Harris's basslines are right up there with Bruce Dickinson in the mix. Judas Priest practically founded metal's now-ubiquitous twin axe attack. It's no surprise that Lemmy prefers Iron Maiden, or that Kerry King champions Priest.
Nowhere are those lightning guitars better heard than in the title track to Painkiller. "Painkiller" doesn't just sound heavy for 1990, or for guys pushing 40. Listening today, in 2013, "Painkiller" is downright brutal, far nastier than any of the power metal it supposedly inspired. Drummer Scott Travis, making his first-ever appearance on a Priest record, wastes no time in implementing blast beats into the Priest formula, and it works shockingly well. Tipton and Downing's solos are so frenetic that even guitar wizard Chuck Schuldiner tried something completely different when he covered "Painkiller" on Death's final album. Rob Halford's frequency-pushing vocals are at an all-time high, perhaps acknowledging that he can go further now to complement his band's flourishing energy. Your parents might have even tolerated "Living After Midnight," but there was no way that they were getting down to this.
You'll hear about how Painkiller was Judas Priest's comeback, a response to two lackluster albums (Turbo and Ram it Down) and a sharply-delivered boot to a world of Poisons and Warrants.
But 1990 was an incredible year for metal. Painkiller was up against Rust in Peace, Seasons in the Abyss and Cowboys from Hell, all Album of the Decade candidates. More than a nail in the glam metal coffin, Painkiller was a gauntlet to the thrash and death metal legions, and an example of how Judas Priest could make a melody sound even meaner than a death growl. Listen to what Amon Amarth did with a similar main riff 18 years later--it completely rocks, but it still doesn't sting the same way.
To paraphrase Ornette Coleman, this is the shape of metal to come.