Bieber and Gaga are still stars.

Kesha flopped after the first single so her

Ke$ha definitely.

Ke$ha is the only correct answer.

Well "C'mon" made it top ten on pop radio and Justin has been slaying radio, digital sales and album copies. I forgot where "MTN" peaked on radio, but it couldn't have been far. "Judas" missed the top ten, "Y&I" strugged to get there (didn't it get there?). And she had to cancel her tour because of bad ticket sales sudden hip surgery.

Let me contemplate.

Ke$ha

Hmmmmmmmmmmmmmmmmmmmm, Ke$ha!

Ke$ha's already in the dark, Gaga's next due to her injury, and Bieber less because he's getting headlines.

Born This Way sold 7+million copies WW
Had 4 Top 10s and gave Gaga another IFPI best selling single

http://www.billboard.com/articles/ne...-at-the-damage

Bieber. He had such a massive era with My World/2.0, he tarnished his rep and lost many of his fans to 1D this era
We're only on K$'s 2nd single, so I'm not voting for her. She could still smash

Gaga. Kesha was never on Gaga's level, so she didn't fade the most.

Judas peaked at #10. Last time I checked, that's still the top ten. How did You and I struggle when it peaked at #6? And NOTTTTT you insinuating Gaga has bad ticket sales when the Born This Way Ball (before the cancellation) out-grossed every pop girl except for Madonna. Not to mention Born This Way sold 6- 7 million WW and had four top ten hits including a song that DEBUTED at #1 and stayed there for six weeks in a row.

There's literally ONE answer