Television hosts Conan O'Brien and Jay Leno have ended their high-profile game of musical timeslots, but the battle for late-night ratings is just beginning. With TBS, CBS, NBC, ABC, and Comedy Central all attempting to crown the next king of late night, has anyone emerged as the frontrunner? Here, five theories:

1. Jimmy Fallon
NBC's "Late Night With Jimmy Fallon" has "moved to the head of its class" since the "SNL" vet took over from Conan O'Brien in March 2009, says Robert Lloyd in the Los Angeles Times. The young host can "sing, and dance more than a little." He's also "an impressive mimic and a good storyteller." The show has jettisoned snark and cynicism in favor of a "spirit of inclusiveness" that "makes it such a good place to hang out on an early morning."

2. Jimmy Kimmel
The unsightly debacle of NBC's late night hosts ripping each other apart, combined with the "giddy cackling" of CBS' David Letterman, "left everyone involved, well, debased," says Dan Fierman at GQ. "Everyone except Jimmy Kimmel." The ABC host emerged as the "conscience of the hoary late-night format," and that alone merits awarding him the title of "the new king of late night."

3. Jon Stewart
"The Daily Show" surged ahead of even its network TV rivals in October, beating both Jay Leno and David Letterman's shows among adults aged 18-49. "It's a notable achievement for Stewart," says Louisa Ada Seltzer at Media Life, giving him the crown — at least for a brief period.

4. Conan O'Brien
The TBS newcomer gave up a lot when he left "The Tonight Show," says Aaron Barnhart at the Kansas City Star. But not only does his new show have great ratings — "well above projections" — it has also captured a large chunk of younger viewers, many at the expense of Stewart and fellow Comedy Central host Stephen Colbert. "If these numbers hold up," they will ensure him "a long future in late night" — maybe even longer than his network rivals.

5. No one
Although the late night line-up features "an abundance of riches that some in the industry quietly believe will never happen again," says David Bauder at The Associated Press, they are up against "a force that's only going to get stronger" — viewers who watch TV on DVR, or just watch next-day highlights. "When the old stalwarts leave, the 12:30 shows could be in danger." We may not see another king of late night.