For me, there should be a kind of beginning and build-up. With a poll simply of 'girl A and girl B catfight; who wins', I tend to wonder, 'catfight in which way, and why do they anyway'.
I like it when, instead, they think they have a reason to compete, when there's a build-up and the situation gets increasingly intense.
The fight could happen in the situation spontaneously, but they could also decide to settle the matter on a mat or in a ring.
Most of all, I'm turned on by contrasts - one female being small and dainty, the other very tall and very strong.
Those one-sided contests don't seem to be liked by most (going by comments everywhere on FCF) but for me they're a big turn-on.
Ideally, the short skinny one is pretty and sexy, and is the 'good girl', the one who 'is right' (like a girlfriend or wife who competes with an obtrusive rival) while her tall, strong opponent is the bad one, the bitch.
I love the thought of competitive comparisons before a fight, the two women comparing their heights, and size of biceps and hands, while the big woman enjoys her amusement and the small one tries to keep up her courage in spite of her obvious disadvantages.
In my typical fantasy, my little skinny and flat-chested wife or girlfriend bravely faces her huge strong opponent endowed with enormous boobs while the other woman laughs at her, toys with her, and finally completely squashes her in the one-sided confrontation.
Intense humiliation for the little flat-chested woman is a big part, for example when her more than one foot taller opponent opponent wedges her face into her huge cleavage until the short girl nearly faints, and later drapes her over her knee and spanks her.
Mom and daughter fights I also find a turn on, for example a thirty year old small skinny woman trying to stand up to her taller and stronger sixty year old mother but getting spanked and humiliated by her.