This season’s “American Idol” Top 2 are both risk-takers, but they show it in different ways. In one corner, there is Adam Lambert, a guyliner-clad stage actor whose appearance alone tells audiences they’d better watch out. It’s not just looks. His standout vocal range gives him a capacity for all sorts of wails. He’s not afraid to use it, even when that means offending country fans with a Marilyn Manson-inspired take on “Ring of Fire.” Then, there is Kris Allen, who at first glance looks like nothing more than the singer you might spot at a local coffeehouse. Just when you expect another botched take on The Fray, he surprises you, delivering a compelling acoustic take on the rap song you thought you hated. This week, Allen and Lambert compete for the eighth-season title. On the surface, Lambert seems to have the advantage. Judge Simon Cowell has publicly predicted he’ll win, and since early in the season he’s seemed like the inevitable champion. But underdog Allen, who received virtually no air time in the show’s preliminary stages, is gaining momentum. His performances at the Top 3 round were enough to oust Danny Gokey, once viewed as a lock for the finals. Only 1 million votes separated Lambert and Allen last week, host Ryan Seacrest said. Suddenly, what was once the most predictable season in “Idol” history has turned into anybody’s game.