I think girls with huge fucking mega milker deluxe tits, thick thighs, and fat asses should be the futanari. And I think these ultra curvy futanari girls should fuck the smaller, more delicate, flatter girls into complete submission until they're struggling to breathe and the heart pupils are imprinted onto their eyes.
I like the idea of the bustiest women breaking smaller, petite girls into little, twitching, moaning puddles. But not only that, I want it to be very clear that the busty women have physically exhausted themselves while fucking these smaller girls. Their hair should be a mess with their bangs disheveled, they should be sweating somewhat, and there should be a very primal and intimate lust on their faces. I don't think it's enough to simply stop at simple sex, I think it should be blatant domination where the smaller/flatter girl is basically the futanari's property afterwards. After being aggressively fucked against every piece of furniture in a room, against a wall, and choked and fucked into the floor, she would no longer normal person. They're just a sex tool for the busty, curvy, ravenous futanari.
The after sex should look like the girl got gangbanged and tossed around like a useless fucking ragdoll, but it was all the work of one futanari with fat fucking tits. That's what I think, anyways.