It's Reigning Divas

On Monday, Oct. 2, the great 1995 pop diva pileup officially begins. Over the next nine days, the four biggest-selling female vocalists of the last decade — Mariah Carey, Whitney Houston, Janet Jackson, and Madonna — will go trill-to-trill. Already, the recording industry is taking bets on which chick will rule the roost.

It begins with warhorse diva Madonna, who debuts the video for ''I Want You,'' a Marvin Gaye cover from her new ballads record, on VH1 Oct. 2. Twenty-four hours later, ingenue diva Carey floods stores with Daydream. At the end of the week, dormant diva Houston's first single in three years, one of two cuts on the Waiting to Exhale soundtrack, is set loose. And on Oct. 10, dynastic diva Jackson's greatest-hits album, Design of a Decade, enters the fray. ''It's quite the battle,'' says Erik Bradley, music director of Chicago's WBBM. ''It's going to be sick.''

It's also divine music for record-store owners. ''Plenty of superstar product has not done particularly well this year,'' says HMV's vice president of purchasing Bob Douglas. Retailers are hoping these new CDs will ignite the holiday season. But who will be queen of the cash register? The tip sheet:

Madonna, Something to Remember (Warner/Maverick, Nov. 7)
Although Maverick artist Alanis Morissette has made Madonna mogul-of-the moment, no one's expecting chart tidal waves for this record — even with three new songs. Why? Because Bedtime Stories fell short of expectations (2 million copies), and this is a greatest-hits collection. ''Um, anytime Madonna does anything it's an event,'' says Z-100 music director Andy Shane diplomatically.

Janet Jackson, Design of a Decade (A&M, Oct. 10)
Hard to believe that Michael's little sis is 29 and ready for a 10-year retrospective. Unfortunately, this greatest-hits collection is somewhat incomplete; only one of the five top-10 hits from 1993's janet. is included. If sales are big, Jackson's already Herculean hand will be strengthened as she shops for a new recording contract — her 1991 Virgin deal was for $32 million. Although Jackson's reportedly talked to every label, including Sony, one observer believes she will sign with David Geffen's DreamWorks label. ''David is most likely to treat her in the style to which she has become accustomed,'' says the source. A Geffen spokeswoman denies any knowledge of meetings with Jackson.

Whitney Houston, Waiting to Exhale (Arista, Nov. 7)
With only two tracks by Houston and the rest by a legion of fellow artists, including TLC, Toni Braxton, and Brandy, this is far less of a Whitney album than her previous soundtrack album, The Bodyguard, was. Her own greatest-hits album, originally due out this fall, has been delayed while she completes a few new songs.

Mariah Carey, Daydream (Columbia, Oct. 3)
Since Carey is the only one with an album of new material, it ''will sell bigger,'' predicts Bradley. This time around, though, Carey is trying to be aggressively street, competing for more of Jackson's audience. While Janet is releasing a remix of her first single, ''Runaway,'' with Coolio, Carey teams with hardcore rapper Ol' Dirty Bastard on the first single, ''Fantasy.''

While the albums are perched for battle, the singles war has already begun. Preliminary results from the Janet vs. Mariah skirmish show Carey's "Fantasy" is in the lead, scoring an enormous coup by debuting at No. 1 on Billboard's singles chart. "The Mariah [song] is a bigger record so far," says John Rogers, music director of Miami's dance station Power 96. ''The people working the Janet record are calling me: 'How are the requests compared to Mariah?' Meanwhile, Janet's ''Runaway'' video has the edge on Mariah's ''Fantasy'' video. According to Billboard, it's won more play on MTV, BET, and VH1.

With this much scrapping over just two singles, the fall could be positively vicious. So far, though, the competition has remained professional, not personal. It may not remain that way. ''When Mariah was in high school she was loving what Janet and Whitney were doing,'' says a Columbia spokesman. ''I'm sure she still does.'' A gracious compliment? Or fighting words? — Additional reporting by Tiarra Mukherjee

Janet Jackson
Number of albums: 5
Multiplatinum albums: 3
Biggest seller: Both 1989's Rhythm Nation 1814 and 1993's janet.sold 10 million copies.
No. 1 singles: 7
Worldwide sales: 25.5 million
Biggest boast: janet. set the record for highest first-week sales by a female (350,000 copies).

Mariah Carey
Number of albums: 4
Multiplatinum albums: 4
Biggest seller: 1993's Music Box (24 million).
No. 1 singles: 9
Worldwide sales: 60 million
Biggest Boast: First female singer to have a song debut at No. 1 on the singles chart.

Whitney Houston
Number of albums: 4
Multiplatinum albums: 4
Biggest seller: 1992's The Bodyguard soundtrack (33.3 million).
No.1 singles: 10
Worldwide sales: 79.5 million
Biggest Boast: 1992's ''I Will Always Love You'' was the longest-running No. 1 single (14 weeks).

Madonna
Number of albums: 9
Multiplatinum albums: 8
Biggest seller: 1984's Like a Virgin (15 million).
No. 1 singles: 11
Worldwide sales: 80 million
Biggest boast: Has had the most No. 1 singles and the most top 10 hits of any female solo artist.