I personally think that Christina Aguilera,but this is an opinion so there's not really a correct answer.
Taylor Swift is the best singer in the world
This time in 2009 the best singer award in male was justin bieber and akon and in female singers Rihanna and selena gomes won the best female singer award.
Joan Osborne - One of us
Gloria Estefan
peggy lee
Taylor Swift is the best singer in the world
There is not really an America's best female r&b singer.
Rihanna
One of them.
Katy Perry won favorite female singer in 2011.
This time in 2009 the best singer award in male was justin bieber and akon and in female singers Rihanna and selena gomes won the best female singer award.
Lily Ivanova
katty perry
helene fischer
Sunitha Nedungadi
Joan Osborne - One of us
Gloria Estefan