Credit: Janet Mayer/PR Photos; Fox; Michael Becker/Fox

Image Credit: Janet Mayer/PR Photos; Fox; Michael Becker/FoxAs American Idol‘s season 10 cattle-call auditions continue — the show stopped yesterday in New Orleans, and will head to New Jersey next week — and the September call-back rounds in front of the judges draw closer, speculation is heating up about who will fill the Simon Cowell Memorial Chair. According to The Hollywood Reporter, former executive producer Nigel Lythgoe, who left the show prior to its eighth season, is thisclose to signing a deal to return to that position for season 10 (alongside Ken Warwick, Simon Fuller, and Cecile Frot-Coutaz); what makes that news especially juicy is the fact that Lythgoe went on the record last spring saying that not only did he prefer a three-judge format for the show (woot!), but that after Cowell’s exit, he favored sweeping the entire judges’ table clean and starting fresh with new panelists (whoa!). The THR story also mentioned that Idol creator Simon Fuller’s current wish list of judges includes Justin Timberlake and Elton John. A Fox spokesperson declined to comment on the Lythgoe rumors or any potential changes at the judges’ table, but here’s a rundown of reported front-runners, along with a few former mentors whose names ought to be included in the conversation. Check ’em out for yourself, then vote for your favorite in our handy PopWatch poll:

Justin Timberlake Pros: Having successfully navigated the tricky voyage from Mouseketeer to boy-bander to solo phenomenon, he certainly has the necessary industry cred for the job, and his knowledge of music written after 1990 could drag the typically fusty Idol panel into the post-Celine era. Plus, as he’s proven on SNL and the ESPYs, his quick wit doesn’t abandon him in front of a live audience. Cons: Hard to think of any, although he’ll need to show a willingness to crush the dreams of talentless kids harboring delusions of singing stardom. One other caveat: It’s not hard to imagine his critiques getting drowned out by continual screaming from overheated teen Swaybots. (Insert shudder of horror here.) Likelihood: He’s reportedly on Simon Fuller’s wish list, but is he too big a star to slum it in reality TV? Possibleeeeee. But it’s worth noting that JT hasn’t released a full-length disc since 2006, and that in recent years, he’s shown considerable interest in discovering, producing, and collaborating with a wide range of artists. Plus, Idol will give him summers off to shoot the occasional big-screen role. Maybe this gig is right up his alley?

Elton John Pros: Sans Simon Cowell, the Idol panel desperately needs a musically credible judge who’s willing to be brutally, deliciously honest, and the notoriously outspoken Elton is one of the few people on the planet who fills both of those requirements — perhaps better than Cowell himself. Lest we forget, this is the man who called the Idol voting process racist after the infamous season 3 Divagate incident that saw Jennifer Hudson, Fantasia Barrino, and LaToya London in the bottom three, while John Stevens and Jasmine Trias stood in safety. Cons: The musical landscape has changed considerably since “Circle of Life” was a radio hit. Can Elton help choose a top 24 filled with viable future hitmakers? (Um, probably.) Likelihood: His was one of the first names that surfaced among Idol fans and media prognosticators when Cowell announced plans to leave the show, and his name surfaced again yesterday. So far, however, there’s been no word from Sir Elton’s camp that he’s interested.

Harry Connick Jr. Pros: His season 9 mentor gig proved he knows how to be affable and honest, and perhaps most importantly, provide the contestants with credible constructive criticism. Cons: Oddly enough, despite Connick’s rock-solid advice and fine arrangements, Frank Sinatra Week wasn’t exactly a musical high point of the season. Plus, his big-band tendencies could shift the contestants toward a less radio-ready sound. Likelihood: Recent experience with the show — and the resulting audience good will it created — are a plus, as was an endorsement from no less than Mr. Cowell himself.

Chris Isaak Pros: Like Connick, Isaak has a mixture of singing and acting experience (including his self-titled sitcom) that should give him an edge getting comfortable in front of the camera. Cons: Honestly, seems a little low-wattage for the gig; it’s been over 20 years since the release of his sole smash hit, “Wicked Game,” which lent an aura of “him? really?” to reports that he’d met twice with Fox brass about taking over Cowell’s seat. Likelihood: If it comes down to a choice between him and the better-known Connick, is there any hope for Isaak?

Usher Pros: Much like Timberlake, Usher has survived the transition from teen sensation to adult superstar, with two slight advantages: He’s got current hits on the radio right this second, and he’s logged time in the Idol-verse, serving as a mentor for R&B Week this past season. Plus, his discovery of ubiquitous Twitter trending topic Justin Bieber gives him the A&R edge over Timberlake and his protégé, YouTube star Esmee Denters. Cons: Brought an encouraging, new-agey vibe to his mentoring sessions — remember how he asked Tim Urban to sing directly to him, like a lover? — that lacked the unfiltered sting of classic Cowell. Likelihood: Lythgoe has previously mentioned Usher as an ideal panelist — and now that the former executive producer is rumored to be reuniting with the show, he has a chance to try and make that dream a reality.

Nigel Lythgoe Pros: The patented British bitchery he brings to So You Think You Can Dance would fit comfortably in Cowell’s Idol chair. Cons: Is there any way to make us miss Cowell more than by replacing him with a pale substitute? Likelihood: Lythgoe is a tough and meticulous presence on SYTYCD — but his expertise is in dance, not singing. Plus, in this critical transitional season, can Lythgoe afford to get distracted from his behind-the-scenes duties? Then again, who’s going to tell the guy he’s not right for the job?

Jennifer Lopez Pros: Okay, so she’s not exactly Barbra Streisand, but let’s flash back for a second to Lopez’s season 6 mentor stint: Not only was she warm and honest and funny, but she seemed genuinely invested in how the contestants performed, almost as if she’d been watching the show all season, rather than having just dropped in for a week to promote her latest disc. And (J)lo and behold, she managed to get a performance out of Sanjaya Malakar that wasn’t completely atrocious. Cons: Yeah, she’s not exactly Barbra Streisand, but you know you wouldn’t change the station if “Waiting for Tonight” came on. Likelihood: Lopez parted ways with her record label in February, and her latest flick, The Backup Plan, underwhelmed at the box office, so maybe it’s time to shake up her career. There are worse places to start than a TV show that draws 20 million viewers per episode.

Shania Twain Pros: Guest-judged the season 9 auditions in Chicago, which just so happened to yield winner Lee DeWyze and runner-up Crystal Bowersox. Better still, Shania was reasonably tough, and occasionally quite funny — so much so that we forgot all about Paula Abdul’s much-discussed absence from the panel. Cons: Nope, can’t really think of any. Likelihood: Already announced plans to launch Why Not? With Shania Twain on The Oprah Winfrey Network next year. Then again, it’s not like she’d be the first Idol judge to juggle multiple projects during a season.

Kara DioGuardi Pros: Stepped up her game and actually offered plenty of constructive criticism to the season 9 finalists, from encouraging Casey James to choose rangier songs to sagely steering Katie Stevens away from country. Cons: Still has a tendency to try to force “Idol Moments” (i.e. rubbing up against Simon; playing up her “cougardom”), but those annoyances began to subside by season’s end. Likelihood: According to THR, her year-to-year contract has yet to be inked.

Randy Jackson Pros: His bejeweled skull t-shirts and jaunty bracelets certainly provide some visual zip to the proceedings! Plus, he’s been on the panel all nine seasons. Cons: Yo, dawg, what’s goin’ down? I don’t know, for me for you, you’ve been kind of pitchy forever, but you did your thing in the end, even though that thing is basically defined by a limited vocabulary, a rambling style of critique, and almost no constructive feedback. Likelihood: Has a contract that would take him through the show’s tenth season.

Ellen DeGeneres Pros: Her season 9 tenure in Hollywood Week proved she was capable of giving honest, sometimes necessarily unpleasant feedback to contestants. Cons: Unfortunately, she abandoned that track once live episodes began in favor of lamely labeling everything “good,” “great,” and “really great.” Likelihood: Has a multi-year deal with the show. Forcing her out could be expensive — from both a monetary and a public-relations standpoint.

How would you cast the season 10 judges’ panel? Vote in our poll below, then sound off with further thoughts in the comments section below! [Related: ‘American Idol’ 15 Ways to Fix It; ‘Idolatry’: Allison Iraheta performs acoustic ‘Holiday,’ talks ‘Glam Nation’ tour; ‘American Idol’ season 9 tour review: Newark, we have a problem!; follow Slezak on Twitter @EWMichaelSlezak.]