Black Sabbath, among other things, is known for songs about Armageddon and sin and plagues. They're known for Ozzy Osbourne's high pitched wail and guitarist Tony Iommi'ssludgy riffs. Their most well-known songs include "Paranoid," "Iron Man" and "War Pigs," all of which can be found on one album, Paranoid. It's not the best Sabbath album with Osbourne--I prefer the sludgier Master of Reality, although I'm sure other folks would go with Sabbath Bloody Sabbath--but it remains the best entryway to the Sabbath canon, if only because most people should already know about half of the album's 42-minute running time.
Compared to the band's discography overall, Paranoid is the moment the band's signature sound began to cohere. Black Sabbath is a downright bluesy affair compared to what came later, and by the time of Reality, the group was into its own sludge-metal world, but Paranoid is the crossroads. It's funny how much of the band's sound was defined by accident--Iommi tuned in D because it was easier on his fingers, the supremely awesome "Paranoid" is as fast/brief as it is because the band needed to turn out another track for the album as quickly as possible, etc--but these decisions mark the beginning of the Sabbath sound even as the group continues to embrace blues riffs on songs like "Jack the Stripper."
Paranoid is a good album, but it has its weaknesses. The second half is notably weaker than the first. "Electric Funeral" is a little silly, even by metal standards. "Rat Salad" is all filler, hence the extended drum solo. "Jack the Stripper" is a decent jammed-out closer, but compared to opener "War Pigs/Luke's Wall," it will always be second best. Still, for all its faults, Paranoid is one of those innovative, influential records that's defined countless other bands.
And I think it's inferior compared to Mob Rules.
Enter Ronnie James Dio. He sang about faeries and dragons and whatever-the-fuck in an operatic singing style, but it's so got-damned fun and infectious that I can't deny his ability. Dude wrote "Rainbow in the Dark" and somehow made the title the most awesomest thing ever. But everything he was good at is different from Sabbath's classic sound. In joining Black Sabbath, Dio essentially bent the band to his will.
Dio-Sabbath is a very different band from Ozzy-Sabbath. The songs are tighter, the hooks are more obvious, even Iommi's playing is different. This shift was further aided by new drummer Vinny Appice, who tapped into Dio's version of metal more by playing on the beat pretty much all of the time, whereas original drummer Bill Ward had a looser style. This is perhaps one of the earliest iterations of what we know call power metal. I should hate this album for erasing everything that Sabbath did during the '70s. But got-damn is it one fun record.
"Turn Up the Night" is a quick number with squealing guitars and propulsive drumming. "Voodoo" is where Dio's penchant for shitty lyrics gets the better of him but, again, it's too hook-laden to ignore. "Sign of the Southern Cross" gets a bit maudlin for my taste, but the band gets things back on track soon after, first with the experimental electronic track "E5150" and then the ridiculously kick-ass fist-pumper "The Mob Rules." Lyrically, it's an argument for researching opinions before going along with popular sentiments, hence the lines "If you listen to fools / the mob rules." The track sums up Dio's brief original run with Black Sabbath (two studio albums and a live record, although Dio returned for 1992's Dehumanizer) with its insistent instrumentals and bravado.
There's a reason why "War Pigs" is so well known. But taken as a whole, I maintain that Mob Rules is the better album. It's more consistent, makes for better driving music and, really, that title track is one badass tune. It's not my favorite Sabbath album--Master of Reality, remember--but when comparing the best of the Dio catalogue with the most classically known Ozzy album, Ronnie proves he deserved his time with one of England's finest metal bands.