Beyonce Vs Britney Vs Christina Vs Gaga Vs Riri Vs Adele Album Sales:
Britney Spears:
Baby One More Time 28 million
Opps i did it again 22 million
Britney 12 million
In the Zone 9 million
Greatest Hits my prerogative 7 million
Blackout 4 million
Circus 5 million
Femme Fatale 3 million
Britney Jean 1 million
Total: 92 million

Beyonce Knowles:
Dangerously In Love 10 million
B'day 7 million
I am Sasha Fierce 6 million
4 2.5 million
Beyonce 3 million
Total: 27.5 million

Christina Aguilera:
Christina aguilera 18 million
Mi Reflejo 3.5 million
Christmas Album 3.5 million
Stripped 11 million
Back to Basics 5 million
Greatest Hits Keeps Getting Beetter 2 million
Bionic 1 million
Lotus .5 million
Total: 46.5 million

Gaga:
Fame+ Fame Monster 15 million
Born This Way 6 million
Artpop 3 million
Tota: 24 million

Riri:
Music in The Sun 1 million
A Girl Like Me 3 million
Good Girl Gone Bad+ Reloaded 9 million
Rated K 3 million
Loud 7 million
Talk That Talk 5 million
Unapologetic 4 million
Total: 31 million

Adele:
19- 7 million
21 - 27 million
Total: 34 million

Katy Perry:
One of the Boys 4 million
Teenage Dream+ Re release 7 million
Prism 3 million
Total: 14 million

Rank:
1. Britney Spears 92 million Congrats Gurl! Its britney bitch!
2.Christina Aguilera 46.5 million
3. Adele 34 million
4. Rihanna 31 million
5. Beyonce 27.5 million LOL
6.Gaga 24 million
7. Katycat 14 million

I haven't included Pink coz i don't want beyonshit to be out of top 5. lol