Pop-cultural eyes and ears are focused on the high-profile hip-hop arrivals - even though they risk having their commercial thunder stolen by cowboy-hatted soft rocker Kenny Chesney, whose Just Who I Am: Poets and Pirates also comes out today.
That's partly because everybody loves a dust-up between seemingly opposite, if equally outsize, personalities. And 50 and Kanye, who stare each other down on the cover of Rolling Stone, certainly fit the bill. It's a hip-hop heavyweight tussle of Ali-Frazier proportions, as well as a desperate effort to salvage another awful year for the music business.
The sales competition has also been cast as a battle for the soul of rap music. West, always given to understatement, has called it "the biggest release date in music-business history," while 50 has said that if he gets outsold, he'll retire.
It hasn't been a good year for the genre, what with the well-respected lyricist Nas setting off a debate with his Hip Hop Is Dead album last December, and foul-mouthed rappers taking the blame after Don Imus called the Rutgers women's basketball players "hos."
But the real worry for rappers in a money-talks culture is that overall music sales are down 15 percent this year, and hip-hop sales a precipitous 33 percent.
Which is where 50 and Kanye come in, two rhymers who have earned the respect of the street while moving enough units to make the mainstream media take notice. While West is honest enough to admit that the hyped-up rivalry is "purely a marketing scheme," as he said Sunday on MTV, that hasn't stopped his musclebound competitor from talking trash.
Fiddy told Rolling Stone that West is "safe . . . more acceptable to conservative Americans like Oprah Winfrey."
He uses "conservative" as a put-down, but the word could be applied to his own career. As a music-maker, Fiddy - who lives in a Connecticut mansion and is said to have made upwards of $100 million when Coca-Cola purchased his stake in Vitamin Water - takes no chances.
That's the problem with Curtis. We can grant 50 metaphorical license and suppose that tracks such as "I'll Still Kill," which features Akon singing a malevolent hook, or "Man Down (Censored)" in which the rapper vows to "murder" his enemies, are not to be taken literally.
Though the album cover showing Fiddy's furrowed brow suggests an intimate, personal statement, it would be disappointing to both fans and foes if the rapper, now 32, were to become soft and repentant. Rugged gangsta rap, mixed in with catchy-if-crude thug come-ons, are what he does. But while he did it thrillingly, and chillingly, on his 2003 debut Get Rich or Die Tryin', the formula has grown deadening.
At least his second CD, The Massacre, boasted "A Baltimore Love Thing," an exploration of addiction, hinting that 50 was thinking deep thoughts beneath his bulletproof exterior. On Curtis, would-be bangers like "Straight to the Bank" play to the cheap seats with boastful menace, but are numbing in their predictability.
The best Fiddy has to offer are the Timbaland-produced "Ayo Technology" (whose twitchy beat and hook sung by Justin Timberlake almost save the witless lyrics ("I'm tired of using technology / Why don't you sit down on top of me?") and "All of Me," on which Mary J. Blige makes the line "I got a feeling like a fiend on crack" sound deeply felt.
West's Graduation is far riskier, and far more successful.
West, 30, isn't as consistently inspired and brilliant as he tells the world he is. "I look at me and Justin [Timberlake] as like Prince and Michael Jackson in their day," he recently claimed. (Which brings to mind the song by the late British songwriter Kirsty MacColl: "You Just Haven't Earned It Yet, Baby.")
But West does earn himself a position as one of the most compelling figures in pop. He has a self-analytical - or perhaps solipsistic - streak that leads him to question his every action, as on the single "Can't Tell Me Nothing" ("I feel the pressure, under more scrutiny / And what I'd do? Act more stupidly.")
He reaches far and wide in search of beats with which to storm the charts. "Stronger" - which has the album's most quotable rhyme ("You know how long I've been on ya? Since Prince was on Apollonia / Since O.J. had Isotoners") - employs the kinetic groove of French electronic duo Daft Punk's "Harder, Better, Faster, Stronger."
West's experiments don't always work. "Champion" proclaims its consciousness-raising ambition by evoking Lauryn Hill, but the endless repetition of its hook, from Steely Dan's "Kid Charlemagne," grows grating fast.
Still, if you're looking for signs of life in rap this Sept. 11, Graduation is where you'll find them. Where Curtis is lazy in its arrogance, Graduation is creatively restless. It'll be bad news for hip-hop if 50 is the big winner at the cash register. But no matter who sells more, West's music wins in the end.
Contact music critic Dan DeLuca at 215-854-5628 or email@example.com. Read his blog, "In the Mix," at http://go.philly.com/inthemix.