Gaga. TF & TFM era were very successful.

Legend X. Her Emancipation Of Mimi is coming

They will collaborate and make a diamond duet album

...And?

Gaga.

Predicting their future 1 year from now would be more realistic

Christina. Gaga's ego is way too big to collaborate with someone to get a hit.

About the same

X's last 5 years >>>>>>> Gaga's 5 years

Xtina's more successful than Gaga right now almost 20 years into her career. Nothing will change in the next 5 years.

Global iTunes Artist Ranking -

31 Christina Aguilera
33 Lady Gaga

- http://kworb.net/itunes/

Lady Gaga, this is too much now sis. You can't compare Xtina who can't go on tour because she can't sell tickets. I know ARTPOP era is mess and underperformed, but still..

Can't find her in the highest grossing tours list though?

Xtina

Gaga obviously

X did a concert in Russia earlier this year, and got paid over 5 milli. That'll be a higher gross than multiple Artpop dates.

TF/TFM alone is more successful than Xtina

Xtina.