Right now, I would say it's currently a toss up between Kelly Clarkson and Carrie Underwood as to who is the most popular American Idol winner. Over time, though, I believe that it will more than likely end up that Carrie Underwood becomes the most popular American Idol winner.
While Carrie may have only recently released her second album (Carnival Ride), her debut album (Some Hearts) has sold at a faster rate than Kelly Clarkson's first album did. Also, I think Carrie is more likely to have crossover appeal (not only can Carrie appeal to the country audience, she can also appeal to pop and adult contemporary audiences as well). Kelly, while she may have the pop and adult contemporary appeal, is much less likely to find any real success on the country charts. And it also doesn't help that Kelly's third album, My December, didn't sell as well as her previous efforts.
So far, it looks like Jordin Sparks won't be much of a contender for the title of the "most popular American Idol winner." Her self-titled debut album recently debuted at number ten on the Billboard Top 200 album chart. This debut position was not only the lowest debut for an American Idol winner's album, it also sold the least amount of copies its opening week compared to other albums released by American Idol winners. Taylor Hicks, the American Idol winner in 2006, is now without a record label, after only selling 690,000 copies of his debut album. And second season winner Ruben Studdard is now also without a label, after J Records reportedly dropped him near the end of 2007.
The seventh season of American Idol has just started, so its way too early to tell how successful the winner of this season will be. However, from what information we have at the time of this writing, it appears that Carrie Underwood will have the greater potential to maintain her popularity and be the most popular American Idol winner.
