I think left is probably the threatening of the two, but right would win in the end.
Right from the start Left is more domineering, she is sure that she can win and that her opponent is not up to her. They both have big tits but left is sure that the couple has considerably more strength.
Right, however, is determined, she wants to put Left in his place due to his behavior towards her. Right is more defensive at first, but she starts to catch up when left underestimates her.
In the end, right submits left with her best match. Left can no longer take the titfight with her bruised tits, the pain is too much for her to bear and she falls to her knees after the final meaty slap between their breasts.