Sisters Vs Cousins

[CF987]

The redhead sisters (left) are skinnier with a little more stamina. The cousins (right) play fight a lot growing up but have less stamina.
The two older siblings (jean shorts and blue dress) had a hard on for each other since college, one day at a bar they saw each other and a loud argument turn physical quickly, their siblings were there so it became a catfight between the pair.
Which pair wins?

[CF987]