It's actually Beyoncé, P!nk and Kelly Clarkson.

Yes actually Gaga is one of the best these days actually... christina and bey have always had good voicals.

Yes in this order:

Xtina

Beyonce/Gaga I think they are equal. Beyonces vocals are highly overrated. These two can sing just not as good as xtina..

Kelly, Beyonce & P!nk if we're only talking about pop girls.

Xtina > Beyonce >>> Kelly >> Gaga > Pink >>> Rihanna > Kesha >>>> Britney

Xtina has the best. I would put Beyonce and Gaga on the same level. People are discrediting Gaga more than they should, she has a voice better than most pop girls.

Xtina > Bey > Gaga

Yes. 3 of the only few vocalists today. Of course P!nk and K clark are good vocalists too but they lack something Gaga, X and KingB has.

The order is:

Kelly > Xtina > Bey > Ariana > Pink > Demi > Gags > the others

replace Gaga with Kelly Clarkson and add P!nk Leona & Nicole Scherzinger, then yes.

+1

Out of current girls, IMO:

Top tier: Beyonce, Christina, Kelly (best ranges, different strengths/weaknesses with delivery/tone)
2nd tier: Pink, Gaga, Adele (Less range, good power and delivery)
3rd tier: Rihanna (decent power and range, but inconsitent)
4th tier: Taylor, Katy (capable but weak vocals)
5th tier: Britney, Madonna (weak vocals)

Nope.

Christina, Kelly & Adele.