All have their strengths and weaknesses - if they can even be convinced that the job is right for them.
But what CNN U.S. President Jon Klein could use is someone to shake up the mix, a candidate no one has anticipated that will make people sit up and take notice. The choice will likely define Klein's legacy at CNN, one that is troubled now because of the continued ratings dominance of Fox News Channel and the emergence of MSNBC as a colorful competitor.
He has indicated that he wants a new show that doesn't stray far afield from King's mission.
"We will continue to do a provocative, topical, intelligent newsmaker interview show every night," he said, "but the format and the style is going to depend a lot on the host - their interests, their style, their approach. Step one is get a host and build the show around them."
None of CNN's competitors have a similar show, he said. "It's an important tool in the arsenal and we want to keep it going," he said.
That would seem to eliminate the idea of moving Anderson Cooper's 10 p.m. ET program up an hour. Cooper has carved out an aggressive news persona, quick to travel to the scene of news and, in the oil spill story, aggressively go after BP. He also has ratings problems, and may not wish to change direction to appeal to King's audience.
King's anniversary week lineup of guests - President Barack Obama, LeBron James, Bill Gates and Lady Gaga - illustrated a versatility that's not easy to come by. His simple interview style often has been derided, but not everyone can be equally comfortable with presidents and pop stars.
CBS News anchor Katie Couric has been the most frequently mentioned potential successor, in part because of the skill she displayed as an interviewer on the "Today" show, which is underused in her CBS job.
"There are a lot of potential hosts of this sort of show," Klein said. "There aren't a ton of them; there are a finite number of them. Katie is certainly one of them."
Couric would have a huge challenge, though. It could not have been easy moving to CBS and being perceived as a savior for a third-place news show - one that's still in third place. Moving to CNN and facing the same pressure at a much smaller network would be a tough sell.
Several published reports say CNN has expressed interest in Britain's Piers Morgan. He's supposedly shown skill as an interviewer overseas; most Americans know him only as someone who judges amateur singers and dancers on "America's Got Talent."
King's favored successor is Ryan Seacrest.
"I've never gotten into deep political discussions with him," King said. "But I would say if he has a working knowledge of politics, he's as good a generalist as there is in broadcasting. If I ran a network, I'd hire him."
Besides questions about his news acumen, Seacrest's involvement in "American Idol" would be a complication. Could he possibly do both, if his CNN show is taped in advance? It might be too much even for someone who has shown a willingness to work.
Bill Maher, King's guest Tuesday when he announced his departure, is politically knowledgeable. But he clearly comes from the left; such a hire would lead to questions about whether CNN is serious about an image of being nonpartisan in its approach. He has also recently signed a contract extension with HBO. The problems are similar for Jon Stewart or Stephen Colbert, both tied into long-term deals at Comedy Central.
Hiring a more news-oriented person, such as PBS' Gwen Ifill, would signal a clear step in another direction for the program.
An out-of-the-box hire could be CNN's best option. When its sister HLN network hired comic Joy Behar of "The View" for a prime-time show, the choice seemed odd. But it has worked much better than anyone anticipated, so much so that Behar's name is also in the conversation as a King replacement.
Perhaps there's another comic, or an actor such as Ben Affleck who would like to be seen in a different light.
Maybe it's unfortunate that former "Tonight" show host Conan O'Brien got another job. He went on Twitter Wednesday to post his reaction to King's decision: "Larry King is retiring after hosting `Larry King Live' for 25 years. Personally, I think hosting anything longer than seven months is overkill."
CNN is unlikely to have any on-air tryouts for the job.
Klein's network has the opportunity to remake its struggling prime-time lineup in a rapid stroke. The hiring of disgraced former New York Gov. Eliot Spitzer to co-host an 8 p.m. political discussion show wasn't greeted with unanimous praise, even reportedly in his own newsroom.
Finding the next Larry King makes for a challenging summertime assignment.